Autotrofic sulfur denitration chamber and calcium reactor

ABSTRACT

The present invention describes novel biological systems and methods for efficiently reducing nitrate levels and otherwise conditioning aquarium water and water in similar environments, and the use of catholyte and anolyte for the improved conditioning of water in aquariums and improved growing conditions for aquatic life.

RELATED APPLICATION

This is a continuation-in-part of prior application Ser. No. 10/673,634filed on Sep. 30, 2003 now U.S. Pat. No. 7,025,883.

FIELD OF THE INVENTION

The present invention relates to apparatus and methods for conditioningwater in aquariums and similar environments for holding fish,invertebrates, mammals, and other aquatic creatures, including coral.More specifically, the invention relates to denitration reactor systemsand methods for removing nitrates and otherwise conditioning water foraquatic purposes in fresh water, brackish water, and salt waterapplications.

Additionally, the present invention relates to the use of catholyte andanolyte with the apparatus and methods of the present inventionresulting in improved conditioning of water in aquariums and improvedgrowing conditions for aquatic life.

BACKGROUND

The accumulation of nitrates is a major problem in both salt and freshwater aquariums and similar aquatic environments. Nitrates build uprapidly in these environments due to fish waste and the regular additionof food, which contains nitrogenous compounds. At high enoughconcentrations, nitrates are noxious to aquatic life. To address thisproblem, polluted water from aquariums is replaced with new waterfrequently in order to maintain a healthy aquarium. The dumping ofnitrate polluted water into the environment furthers the nitratepollution of water supplies worldwide. This water changing is timeconsuming and may be expensive to both aquatic hobbyists and keepers ofcommercial aquariums alike, especially if the aquarium is a salt wateraquarium that is not in close proximity to the ocean or other sources ofunpolluted aquarium water.

Various methods, other than water changes, are known in the art forremoving nitrates from aquariums. One common method is the use ofprotein skimmers to eliminate nitrogenous compounds before they aretransformed into nitrates. Protein skimmers are constructed in a tube ortower having a collection cup at the top. These skimmers work byinjecting massive amounts of very fine air bubbles into the tube. Therising air bubbles act as a lift in the tube, allowing the undesirablenitrogenous compounds to attach to the bubbles and rise to the surface,where they are captured in the collection cup and disposed of.

Another method for reducing nitrates involves using bacteria. Examplesof such systems are described in U.S. Pat. No. 4,995,980, to Jaubert; anarticle entitled “Nitrates Elimination by Autotrophic Denitration onSulfur,” by Christophe Soler; and an article by Marck Langouet,entitled, “The Autotrophic Denitration on Sulfur What's the Status?.”

SUMMARY OF THE INVENTION

It is an object of the present invention to provide improved methods andsystems for conditioning water in aquariums and similar environments.

The present invention includes novel biological systems and methods forefficiently reducing nitrate levels and otherwise conditioning aquariumwater and water in similar environments. The methods and systems of thepresent invention maintain a healthy and efficient aerobic bacteriaculture, reduce ammonia in the water to nitrite and nitrite to nitratein an aerobic process, reduce oxygen in the water and generate CO₂before the water is treated by anaerobic bacteria, maintain a healthyand efficient anaerobic bacteria culture, insure that a sufficient foodsupply is maintained for the bacteria culture, efficiently reducenitrates to acceptable levels, control the pH to within safe levels, addhealthy minerals to the water, and reduce odors caused by the productionof hydrogen sulfide gas formed in the autotrophic denitration process.The systems of the present invention are light in weight relative to thesize of the aquarium or similar closed environment of water, are easy touse, need little maintenance, and are unlikely to clog or overflow.

The invention also includes the addition of negative ions into theaquatic systems for the benefit of the aquatic life within the systems.The health benefits of ionized air, more specifically negative ions inthe air, are well known. Similar health benefits occur from the presenceof negative ions in water. For example, negative ions in the water areabsorbed in the bloodstream of the aquatic life, and help the animalsprocess the food more efficiently. As a result, the animals need lessfood to remain healthy, and improved health leads to faster growth.

This invention also includes the addition of anolyte and catholytesolutions to the water during the conditioning process. Anolyte andcatholyte are activated solutions produced by a process calledelectro-chemical activation known in the art. Machines capable ofproducing these solutions are commercially available.

In the present invention, anolyte serves as a very powerful disinfectantagainst bacteria, viruses, and algae. The anolyte used according to thepresent invention is a neutral anolyte, preferably having a pH rangingfrom about 6.5 to 8.5.

In the present invention, catholyte and anolyte are used to improve thequality and efficiency of water conditioning. The catholyte used in thepresent invention is an alkaline catholyte, preferably having a pHranging from about 11 to 13. Alkaline catholyte solutions have numerousapplications in the water conditioning systems and methods of thepresent invention, and can provide several benefits. For example,catholyte solutions prove useful for flocculation (e.g. of heavymetals), coagulation, washing, and extraction. Additionally, catholytesolutions can also promote the health and growth of organisms used inthe treating processes of the present invention. As a result, the wateris processed more efficiently, which can reduce the number of filtersnecessary to achieve the desired effect in the aquatic systems. Finally,catholyte is a liquid source of negative ions, and is beneficial to theaquatic life in the systems as well. As discussed above, these negativeions can improve the health, feeding rate, and growing rate of theanimals.

One embodiment of the present invention is directed to a process forconditioning aquarium water or other closed environments for aquaticlife. The process comprises flowing water through a first chambercontaining a first media supporting aerobic bacteria and then flowingthe water through a second chamber containing a second media comprisingsulfur that supports an anaerobic bacteria that will reduce nitrates tonitrogen gas through a biological process. In a preferred embodiment, asupply of catholyte solution is added, directly or indirectly, to thewater at this denitration step. The catholyte will be added in an amountthat will improve the health and the growth of the bacteria in thesystem, which will help remove nitrates. Preferably, the catholyte isadded in an amount that ranges from about 1 to about 20 percent of thetotal volume of the water flowing through the system, and morepreferably from about 5 to about 20 percent. In a preferred embodiment,the catholyte is produced on site by a machine that creates catholyteand anolyte from water in an electrochemical process. The supply offreshly produced catholyte is applied directly to the system from themachine or a holding tank.

Preferably, the aerobic bacteria are capable of reacting with ammoniaand nitrites in the water to generate nitrates, while also generatingcarbon dioxide and significantly decreasing the level of oxygen in thewater to a minimum level. Preferably, the anaerobic bacteria are capableof being supported by the sulfur substrate even at times when the waterbeing treated contains little or no nitrates. One such type of bacteriais Thiobacilus denitrificans, although other bacteria may be used asdiscussed below. The denitration process achieved by these bacteriareduces nitrate concentrations in the water, while at the same timedecreasing the pH of the water. Preferably, the water is then flowedthrough at least one chamber to increase the pH of the water. By meansof example only, the chamber might contain a calcium source. As waterflows through a calcium chamber, the calcium source reacts with hydrogenions in the water to increase the pH of the water. Preferably, the waterflows from the sulfur chamber through multiple chambers having differentwater treatment characteristics. In one embodiment, several chambershave different calcium sources. Additionally, catholyte can be added tohelp increase pH.

In salt water applications, especially ones having live coral, the useof multiple chambers with different calcium sources is highly preferred.These chambers in the preferred embodiment include dolomite, thenaragonite, and then calcite, or other forms of calcium that respectivelyhave the qualities and characteristics of these preferred forms ofcalcium. The water may then be flowed through one or more additionalchambers or devices for degassing the water, removing additionalcontaminants, as well as adding oxygen to the water, before the water isreturned to the aquarium.

In one embodiment, a sufficient supply of catholyte is added to thewater as it is returned to the aquarium. The catholyte in the aquariumwill improve the health, feeding rate, and the growing rate of theanimals. The catholyte is not toxic, and after a short time, thecatholyte converts back into water. In an alternative embodiment, aconstant flow of water in the tank is removed from the tank and mixedwith catholyte as it is circulated back into the tank through a mixingeductor, The catholyte can be added in an amount sufficient to improvethe health and growth of the bacteria in the system, such as from about1 to about 20 percent of the total volume of the water flowing throughthe system.

Another embodiment of the invention is directed to a biological systemfor conditioning water in an enclosed environment for aquatic life. Thesystem comprises a first chamber containing a first media capable ofsupporting aerobic bacteria. A second chamber is connected to the firstchamber by a first pathway through which the aquarium water flows. Thesecond chamber contains a second media, preferably sulfur, that iscapable of supporting anaerobic bacteria, such as Thiobacilusdenitrificans bacteria. A third chamber, which contains a first calciumsource, may be connected to the second chamber by a second pathwaythrough which the aquarium water flows. Additionally, a fourth chamber,containing a second calcium source, may be connected to the thirdchamber by a third pathway through which the aquarium water flows. In apreferred embodiment, a fifth chamber may be added for containing athird source of calcium. Preferably, the system includes one or moreadditional chambers or devices for degassing the water before the wateris returned to the aquarium. A preferred embodiment of the presentinvention includes devices designed to minimize water loss during thefiltration process such that little or no water needs to be added to theenclosed environment.

As explained below, the methods and apparatus of the present inventionmay be used alone, or in connection with other filtration systems, andmay be applied to large and small aquariums, to provide clean andhealthy water to aquatic life in an efficient and economic way that doesnot harm the environment. The disclosed methods and apparatus can alsobe used, in whole or in part, in other applications where toxic nitratesmust be removed from water and the water must be efficiently andeconomically treated. For example, the denitration and treatmentprocesses of the present invention can be applied to aquatic farms,livestock farms, sewage treatment, the purification of drinking water,industrial waste water treatment, and similar applications wherenitrates are generated in the water supply and must be controlled, alongwith other aspects of the water.

These and other embodiments of the invention will be discussed morefully in the detailed description of the embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate exemplary embodiments of theinvention and, together with the written description, serve to explainthe principles of the invention.

In the drawings:

FIG. 1 a is a process flow diagram representing the flow of the variousprocess steps which may be used for conditioning water, according to thepresent invention.

FIG. 1 b is a flow diagram showing the steps where catholyte and anolytemay be added, according to the present invention.

FIG. 2 a is a diagrammatic representation of one system for conditioningwater for aquatic life, according to the present invention.

FIG. 2 b is a diagrammatic representation of a system for conditioningwater for aquatic life including a device for making catholyte andanolyte, according to an embodiment of the present invention.

FIG. 3 is a diagrammatic representation of a chamber containing floatingmedia capable of supporting aerobic bacteria, according to an embodimentof the present invention.

FIG. 4 is a diagrammatic representation of a denitration chambercontaining sulfur media capable of supporting anaerobic bacteria,according to an embodiment of the present invention.

FIGS. 5 and 6 are diagrammatic representations of chambers of thebiological system which contain arrangements of media comprisingcalcium, according to certain embodiments of the present invention.

FIG. 7 is a diagrammatic representation illustrating certain dimensionsof one chamber of the biological system, according to an embodiment ofthe present invention.

FIGS. 8 a to 8 c are diagrammatic representations of top and side viewsof arrangements of the various chambers of the biological system,according to an embodiment of the present invention.

FIG. 9 is a diagrammatic representation of denitration chamberscontaining sulfur media capable of supporting anaerobic bacteria,according to an embodiment of the present invention.

FIG. 10 is a diagrammatic representation of sulfur containing mediacapable of supporting anaerobic bacteria, according to an embodiment ofthe present invention.

FIG. 11 is a diagrammatic representation of denitration chamberscontaining sulfur media capable of supporting anaerobic bacteria,according to an embodiment of the present invention.

FIG. 12 a is a diagrammatic representation of a further embodiment ofthe biological system having a chamber containing sulfur and a chambercontaining calcium, according to the present invention.

FIG. 12 b is a diagrammatic representation of a further embodiment ofthe biological system similar to the embodiment of FIG. 12 a, but havingan additional chamber containing a media for aerobic bacteria.

FIG. 13 is an additional diagrammatic representation of the biologicalsystem of FIG. 12, which shows an outside view of the system, includingdetails of the air pumping system in relation to the inlet and outletpipes.

FIG. 14 is a three dimensional view of the biological system of FIG. 8,according to the present invention.

FIG. 15 is a three dimensional view of a biological system comprisingmultiple sections arranged in a single cylindrical chamber, according toanother embodiment of the present invention.

FIG. 16 is a diagrammatic representation of an activated carbon chamber,according to an embodiment of the present invention.

FIG. 17 a is a diagrammatic representation of a system for conditioningwater for large aquariums, according to an embodiment of the presentinvention.

FIG. 17 b is a diagrammatic representation of a system for conditioningwater for large aquariums including a device for making catholyte andanolyte, according to an embodiment of the present invention.

FIGS. 18 a through 18 c are diagrammatic representations, including sideand top views, of a chamber which utilizes algae to remove contaminantsfrom water, according to an embodiment of the present invention.

FIG. 19 a is a diagrammatic representation illustrating the placement ofa light source within a chamber which utilizes algae to removecontaminants from water, according to a further embodiment of thepresent invention.

FIG. 19 b is a diagrammatic representation of a light source which maybe used in the chambers illustrated in FIGS. 18 and 19 a, according toan embodiment of the present invention.

FIGS. 19 c and 19 d are diagrammatic representations, including a sideand top view, respectively, of a light source which may be used in thechambers illustrated in FIG. 18, according to an embodiment of thepresent invention.

FIGS. 20 a to 20 e are diagrammatic representations illustrating variousprotein skimmer embodiments, according to the present invention.

FIGS. 21 a to 21 d are diagrammatic representations illustrating aneductor for mixing fluids, according to an embodiment of the presentinvention.

FIGS. 22 a and 22 b are diagrammatic representations illustratinganother embodiment of an eductor for mixing fluids, according to thepresent invention.

FIGS. 23 a to 23 f are diagrammatic representations illustrating achamber for removing sulfates, according to an embodiment of the presentinvention.

FIG. 24 illustrates an aerobic chamber, according to an embodiment ofthe present invention.

FIG. 25 illustrates a calcium chamber, according to an embodiment of thepresent invention.

FIG. 26 a illustrates a system for filtering water in aquariums or aquaculture applications, according to an embodiment of the presentinvention.

FIG. 26 b illustrates a system for filtering water in aquariums or aquaculture applications that includes the addition of catholyte andanolyte, according to an embodiment of the present invention.

FIG. 27 illustrates a bio-filter chamber, according to an embodiment ofthe present invention.

FIG. 28 illustrates a drain system for minimizing water loss, accordingto an embodiment of the present invention.

FIG. 29 illustrates another bio-filter chamber, according to anembodiment of the present invention.

FIGS. 30 a and 30 b illustrate a support for a mixing eductor used inthe bio-filter chamber of FIG. 27, according to an embodiment of thepresent invention.

FIGS. 31 a and 31 b are diagrammatic representations of the use ofanolyte and catholyte for cleaning aquatic tanks.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, reference is made to the accompanyingdrawings, which show, by way of illustration, specific exemplaryembodiments in which the invention may be practiced. These embodimentsare described in sufficient detail to enable those skilled in the art topractice the invention, and it is to be understood that otherembodiments may be utilized, and that changes may be made withoutdeparting from the scope of the present invention. The followingdescription is, therefore, not to be taken in a limited sense. Whereverpossible, the same reference numbers are used throughout the drawings torefer to the same or like parts.

The methods and systems of the present invention can be applied todifferent types of aquariums and similar environments for aquatic life,in both fresh water and salt water applications. The systems and methodsof the present invention can be designed to control the quality of watersupporting fish, as well as coral and other aquatic life, in a varietyof different aquariums and similar environments, ranging from relativelysmall household aquariums to aquariums of millions of gallons, or more.While the broadest principles of the invention are applicable to many,if not all, of these potential applications, preferred methods andsystems are disclosed for specific applications, or ranges ofapplications.

The physical characteristics of the systems of the present invention canvary considerably, while still practicing the present invention.Examples of some, but by no means all, of the potential embodiments ofthe present invention are shown in FIGS. 2 through 31 b.

FIG. 1 a is a process flow diagram illustrating various process steps 1to 8 of the present invention, which will now be used to describe theprocess of the present invention in general terms. All of the processsteps shown in FIG. 1 a are not required for every embodiment of theinvention. Rather, the process steps utilized may be chosen as desiredto meet the requirements of the aquarium, or other aquatic system, forwhich the process is employed. Examples of preferred embodiments of theinvention will also be provided.

Referring to FIG. 1 a, the process of the invention may comprise afiltration step 1, in which the water to be treated passes through afilter, followed by an aerobic bacteria processing step 2, and ananaerobic bacteria processing step 3. Additional process steps mayinclude steps for adding desirable nutrients to the water, such ascatholyte or anolyte, adjusting pH, reducing undesirable gases, addingoxygen to the water, or any other step which is desirable for furtherconditioning of the water. For example, in steps 4 and 5, the waterbeing processed is flowed over two separate chambers to add calcium andincrease pH. Catholyte may be added to the calcium chambers to increasepH as well. In one embodiment, the water flows over two separate calciummixtures. Step 6 represents a degassing process wherein the water isflowed through a degassing chamber which, among other things, removesundesirable gases and compounds from the water. Alternatively, or inaddition to degassing step 6, a process step 7 may be used for reducinghydrogen sulfide gas from aquarium water by flowing the water through anactivated carbon chamber. Still another alternative process isrepresented by step 8, in which water is flowed through a chamber,termed “the oxytower,” which contains algae and/or bacteria in order toremove certain undesirable contaminants, increase pH, and add oxygen tothe water. Each of these steps is not necessary for each potentialapplication to a particular aquarium or problem.

Referring to FIG. 1 b, the process of the present invention preferablyincludes the addition of catholyte. As shown in FIG. 1 b, catholyte isproduced from an external source, and can be added to the water at anytime before step 1 through the end of step 5. The catholyte can be addedin a single step, or in multiple steps. In a preferred embodiment, thecatholyte is produced on site by a device that crates catholyte andanolyte from water in an electro-chemical process. The supply of freshlyproduced catholyte is applied directly to the water from the machine ora holding tank.

The process steps shown in FIG. 1 a may each be performed in separatechambers. Alternatively, two or more of the process steps may beperformed in a single chamber or a chamber or housing having multiplesections devoted to each of the process steps performed therein.Examples of systems for carrying out the processes of the presentinvention will be provided in the form of preferred embodimentsdiscussed herein.

The process steps of FIG. 1 a are associated with each other so thatwater to be treated flows from the aquarium 10, or other closedenvironment, through one chamber to another and then returns to theaquarium. The system in which the process steps of FIG. 1 a occur willat times be referred to herein as the Nitrafix system.

The water to be treated may flow directly from the aquarium to theNitrafix system, and then return to the aquarium. Alternatively, theaquatic system may include a sump 9, as shown in FIG. 1 a. Such sumpsare known in the aquarium art for collecting, filtering and otherwisetreating aquarium water outside of the aquarium tank. Water flows fromthe aquarium tank to the sump and then returns to the aquarium tank. Allor a portion of the water flowing from the sump may be diverted to theNitrafix system for processing before the water is returned to theaquarium tank. After processing by the Nitrafix system, the water may bereturned either to the sump, as shown in FIG. 1 a, or directly to theaquarium tank.

Generally, the flow rate through the sump is approximately three timesthe volume of the aquarium per hour, as is conventionally known. Theamount of water flowed through the denitration system of the presentinvention is significantly less. For example, it has been found that thewater applied to the denitration chamber according to the presentinvention can be about 1% of the volume of the aquarium per hour, andperform well. The particular flow rate for a specific application can bevaried and optimized through routine testing. A flow rate ranging fromabout 1% to about 10% of the volume of the aquarium per hour is believedto be optimum for most applications, although about 1% to about 3% maybe more preferable for aquarium applications.

The means for forcing the water through the Nitrafix system may be anymeans known in the art, such as use of an air pump, air stone ormechanical pumping device. A gravity feed, such as where the water issiphoned from the aquarium tank to the Nitrafix system may also be used,as is known in the art.

A more in-depth discussion of each of the process steps of FIG. 1 a willnow be provided. Step 1 of the process is an optional filtering step bywhich particulates or other solid matter is removed from the water to betreated. The water to be treated may contain various types of solidmater, such as fish waste, sand, and algae. Removing this solid matterfrom the water not only provides for a cleaner, more attractiveaquarium, but also helps to prevent clogging of the Nitrafix system.This filtration may be accomplished by using a mechanical filter, suchas a screen, or cartridge filter. Other filters known in the art mayalso be used. In order to prevent clogging of the Nitrafix, it ispreferred that the filter remove particulates which are 50 microns orlarger.

In one embodiment, catholyte is added to the water before step 1. Thecatholyte solution is provided from an external source as showngenerally in FIG. 1 b, and may be added to the water by any means knownin the art. Preferably, the catholyte is added by dripping the solutioninto the water as it flows from the aquatic environment to the filter ofstep 1, to ensure the catholyte mixes well with the water before itflows to the bacteria processing chambers downstream. The catholyte isadded in an amount that ranges from about 1 to about 20 percent of thetotal volume of water flowing through the system.

step 2 of the process, shown in FIG. 1 a, uses aerobic bacteriaprocessing to treat the water. The water to be treated is flowed througha chamber which contains a support media that preferably has a largesurface area on which the aerobic bacteria may colonize. Examples ofsuch media include sand, plastic particles, and similar media. Theaerobic bacteria exist and thrive in the aquarium water and willcolonize on the media within the chamber as the system is operated. Thetype of aerobic bacteria utilized in step 2 may include, for example,nitrosomonas and nitrobacter bacteria. These naturally occurringbacteria break down ammonia and nitrites in the aquarium water and formnitrates. In the process of breaking down the ammonia and nitrites, theaerobic bacteria produce CO₂ and reduce the levels of dissolved oxygenin the water. Preferably, the chamber housing the aerobic bacteria, aswell as the media in the chamber, are sized so that most, if not all,oxygen in the water is removed, as the water flows through the chamber.While this chamber preferably breaks down ammonia and nitrites, thechamber could also be designed to use other chemical or mechanicalagents that take all or most of the oxygen out of the water, before itflows through the next chamber, and still be effective in reducingnitrates from the water.

In one embodiment, catholyte is added to the water before step 2. Thecatholyte solution is provided from an external source as showngenerally in FIG. 1 b, and may be added to the water by any means knownin the art. Preferably, the catholyte is added by dripping the solutioninto the water as it flows from the filter of step 1 to the chamber ofstep 2, to ensure a good distribution of the catholyte within thechamber. The catholyte is added in an amount that ranges from about 1 toabout 20 percent of the total volume of water flowing through thesystem.

The total average dissolved oxygen content in water in aquariums withnormal loading and feeding is approximately 5 ppm. Of course, theaverage level of dissolved oxygen for each aquarium may be greater orless than 5 ppm, depending on the fish load and feed supply to theaquarium. It is preferable that the process of step 2 substantiallyreduce the dissolved oxygen content of the water leaving the aerobicbacteria processing chamber, as compared with the level of dissolvedoxygen in the water entering the chamber, in an amount sufficient tosignificantly increase the nitrate reduction in step 3 over what itwould have been if the step 2 process had not been employed. Thus, it ispreferable that the total dissolved oxygen content be reduced to, forexample, less than 5 ppm, and more preferably, to less than 2 ppm, andstill more preferably to about 1.64 ppm or less.

Following the aerobic process of step 2, an anaerobic processing step 3is next employed to autotrophically reduce the concentrations ofnitrates in the water by a process known as sulfur denitration. In thepreferred embodiment, sulfur denitration utilizes sulfur oxidizingbacteria such as Thiobacillus denitrificans. Under aerobic conditions,these bacteria will use oxygen to oxidize sulfur. However, wheninsufficient oxygen is present, the bacteria use nitrate to oxidizesulfur to sulfate. Thus, the reduction of oxygen in step 2 permitsnitrates existing in the water to be efficiently utilized by thebacteria in an anaerobic type process. In this manner, the concentrationof nitrates in the water is reduced in the step 3 process.

In addition to reducing nitrates, the bacteria in the denitrationchamber may also reduce other undesirable nitrogen compounds, such asnitrites. The denitration process also decreases the pH of the water. Itshould also be noted that for the first few days of operation fromstartup, the denitration chamber may produce nitrite. However, theamount of nitrite produced will thereafter decrease and the chamber willpreferably begin to help reduce nitrite levels.

The aerobic process of step 2 helps to insure that the oxygenconcentration is sufficiently decreased, while the nitrate concentrationis sufficiently increased, in order to maintain an efficient anaerobicsulfur denitration process. Consequently, less support media for theanaerobic bacteria is needed to remove the desired amount of nitratesthan if the aerobic process was not used. This allows for a smaller, andsignificantly lighter weight, denitration chamber for the step 3process, since the sulfur media used in the chamber can be relativelyheavy. Additionally, the reduction in the level of dissolved oxygen inthe chamber may help to prevent the proliferation of certain undesirablesulfate reducing bacteria, such as Beggiatoa Alba. Beggiatoa Alba areknown to be filamentous, creating a thick, slimy coating on the sulfurmedia, which could cause the chamber containing the sulfur media toclog.

The aerobic bacteria process of step 2 should preferably occur inlinewith, and in close proximity to, the denitration step 3, so as toprevent reoxygenation of the water before it enters the denitrationchamber.

The applicant believes that it is also possible that carbon dioxideproduced by the aerobic bacteria in step 2 allows the bacteria in thedenitration chamber to remove nitrates more efficiently. However, it isnot intended that the above described mechanisms of the bacteriaprocesses limit the full scope of the invention as defined by theclaims.

The denitration step 3 utilizes a media that supports the anaerobicbacteria that break down nitrates in the water. Preferably the mediawill support the anaerobic bacteria even when there are lowconcentrations of nitrates in the water. In a preferred embodiment, themedia is sulfur and the bacteria is Thiobacilus denitrificans. Asdiscussed above, under the proper conditions where oxygen levels are lowenough, these bacteria carry out anaerobic respiration, reducingnitrates while oxidizing elemental and/or reduced sulfur to sulfate. Forexample, the dissolved oxygen content of the water entering thedenitration chamber is preferably between 0 to 2 ppm. Other conditions,such as the temperature and the pH of the water should also bemaintained at healthy levels for the bacteria. For example, ifThiobacillus denitrificans are employed, the water in the chamber shouldpreferably have a temperature ranging from 25 to 30 degrees Celsius anda pH ranging from about 6 to about 8, although the bacteria may functionoutside of these ranges. Other bacteria which reduce nitrate whileoxidizing sulfur may also be used in place of or in addition toThiobacillus denitrificans. Examples of such bacteria which may beacceptable for use in the present invention include Thiobacillusversutus, Thiobacillus thyasiris, Thiosphaera pantotropha, Paracoccusdenitrificans, and Thiomicrospira denitrificans. The scope of theinvention includes the application of any anaerobic bacteria that cansurvive in a media within a chamber and efficiently and effectivelyperform the denitration process of the present invention on a flow ofwater having nitrates that must be removed.

In another embodiment, catholyte is added to the water before thedenitration step 3, so that the catholyte can improve the health of theanaerobic bacteria. The catholyte solution is provided from an externalsource as shown generally in FIG. 1 b, and may be added to the water byany means known in the art. Preferably, the catholyte is added bydripping the solution into the water as it flows from the chamber ofstep 2 to the chamber of step 3, to ensure a good distribution of thecatholyte within the chamber of step 3. The addition is preferably madein a manner which minimizes the addition of oxygen to the water. Thecatholyte is added in an amount that ranges from about 1 to about 20percent of the total volume of water flowing through the system.

The structure enclosing or creating the denitration chamber ispreferably opaque so that little or no light is in the chamber. This isbecause the anaerobic bacteria do not like light. If placed in a lightedenvironment, the bacteria will move toward the center of the chamberwhere the environment is darker. This would thereby decrease theefficiency of the bacteria in eliminating or reducing nitrates from thewater.

The level of nitrate in the water at the outlet of the denitrationchamber may depend on the amount of nitrate in the inlet flow to thedenitration, the flow rate of water through the denitration chamber, andcontact time of the water with the sulfur media. Under optimumconditions, the denitration chamber may reduce substantially all of thenitrates. For example, nitrate levels at the outlet may range from about0 ppm to about 20 ppm, and more preferably from about 0 ppm to about 10ppm, and still more preferably from about 0 ppm to 5 ppm.

The pH of the water will be reduced during the denitration process.Consequently, the pH of the aquarium water leaving the denitrationchamber may range from about 4 to about 8, and more preferably fromabout 5 to about 7. Such low ranges may not be healthy for some aquaticlife. The pH of the water leaving the denitration chamber may beadjusted by, for example, adjusting the flow rate of the water throughthe chamber. Another way to adjust the pH to desirable levels is to addcalcium to the water. The calcium is beneficial to many sea organisms,such as corals, that use the calcium to form their skeletons and/orshells. Catholyte can also be added to the system to help increase pHlevels. In addition to the health benefits offered from catholyte, thebacteria used in the aerobic and anaerobic processes of the Nitrafix aremore effective if the pH is kept within a healthy range for theparticular bacteria being used, such as, for example, a pH of 6 to 9.Therefore, in closed systems where the water is continually recirculatedthrough the Nitrafix system, using calcium, or calcium and catholyte tomaintain the proper pH can help to make the process more effective.

In order to adjust the pH of the water to the desired range, as well asto add calcium to the water, the process of FIG. 1 a includes steps 4and 5, in which the water leaving the denitration chamber is flowed overmultiple calcium sources. Different calcium sources, which havedifferent solubilities, are preferably used to control not only theamount and type of calcium which is dissolved in the water, but also toincrease the life of the calcium media in the system before new calciummedia must be added. Acceptable sources of calcium include dolomite,aragonite, calcite, crushed coral, as well as other known sources. Thesesources of calcium include other minerals and trace elements, such asmagnesium and strontium, which can also be beneficial to aquatic life.As the water flows through the calcium sources, the calcium sourcesdissolve to add beneficial amounts of the calcium and other elements tothe water, and increase the pH of the water. While FIG. 1 a shows thecalcium being added in two steps, the calcium may be added in a singlestep, or in three or more steps.

FIG. 1 b illustrates that catholyte can be added during any or all stepsinvolving passing the water through calcium chambers to adjust pH. Thisincludes adding water before step 4, before step 5, and after step 5.The catholyte is provided from an external source, and may be added tothe water by any means known in the art. Preferably, the catholyte isadded by dripping the solution into the water as it flows between thechambers used in the calcium addition steps, to ensure the catholytemixes well with the water before it enters the chambers. The catholyteis added in an amount that ranges from about 1 to about 20 percent ofthe total volume of water flowing through the system.

Adding the calcium in multiple steps has the benefit of allowing thecalcium source to be arranged to give long life with a minimum amount ofclogging. For example, the calcium source may be arranged so that thewater coming from the denitration chamber contacts the least solublecalcium sources before the other more soluble calcium sources. This willresult in increased life of the calcium media in the system because theacidity of the water is reduced when it contacts the less solublecalcium sources, so that the water having a reduced acid content willdissolve the more soluble calcium media at a slower rate. Furthermore,very fine media, such as calcite sand, can create clogging problemswithin the calcium chambers. Clogging may be prevented by utilizing alarge media, such as crushed coral, in the same chamber as the calcitesand. Specific examples of how the calcium should be arranged to providefor long life and reduced clogging will be provided in the preferredembodiments.

In certain applications, no calcium may be added by omitting steps 4 and5 altogether. In such applications, the pH of the water is preferablyraised by other means before it is resupplied to the aquarium. In oneembodiment, catholyte is added to the water after it flows out of thedenitration chamber to adjust the pH.

A degassing step 6 may also be added to the process. The degassing stepmay be performed in a degassing chamber in which the water is degassedand reoxygenated before returning to the aquarium tank. The degassingstep provides the advantages of reducing odorous gases, such as hydrogensulfide gas, and other undesirable contaminants, which may be emittedfrom the biological processes occurring within the chambers. Degassingcan also be useful for raising the pH of the water by reducing carbondioxide levels.

For example, in one embodiment a conventional protein skimming step maybe added to the process of FIG. 1 a, which removes undesirablecompounds, such as nitrogenous and other organic compounds, raises thepH, and adds oxygen to the water. Other systems for degassing, which areknown in the art, may also be used for step 6, including a drippingsystem, such as a degassing tower, compressed air through stone, and theVenturi system.

Another optional process step utilizes an activated carbon chamber, asillustrated in FIG. 16. The chamber 20 may be added to the system forreducing levels of hydrogen sulfide gas. When the Nitrafix system isrunning at the desired flow rate, it produces relatively little, if any,hydrogen sulfide. However, when the flow through the Nitrafix system isstopped for a period of time, or if the flow is too low to providesufficient nitrate to the bacteria in the denitration chamber, certaintypes of sulfur reducing bacteria will begin to reduce sulfate tohydrogen sulfide. If large enough amounts of hydrogen sulfide gases areproduced, this can be lethal to aquatic life, such as fish. In order toreduce the amount of hydrogen sulfide generated by the Nitrafix systemduring these down times to acceptable levels, an activated carbonchamber 20, as illustrated in FIG. 16, may be employed. Such a chambermay also reduce other gases that are generated through the process ofthe present invention.

In one preferred embodiment, chamber 20 is filled with activated carbon21. The chamber 20 comprises an inlet 22 for allowing water to flow intothe chamber, which is located a distance “A” from the top of thechamber, and an outlet 23 located near the bottom of the chamber. Waterentering chamber 20 flows down through wet zone “B” of the activatedcarbon chamber, which acts to degas and adsorb contaminants, includinghydrogen sulfide gas in the water. Gas emissions, including hydrogensulfide gas, flow up through dry zone “A” of the activated carbonchamber and out through vents 28. The hydrogen sulfide gas is adsorbedby the activated carbon in the dry zone, thus reducing the “rotten egg”smell which is characteristic of hydrogen sulfide gas. Screens 26located at the mouths of inlet 22 and outlet 23 help prevent the chamberfrom becoming clogged.

Preferably, chamber 20 is employed in the process after the denitrationstep and before the water is returned to the aquarium tank. For example,chamber 20 may be employed directly at the outlet of the denitrationchamber, or after the calcium chamber or chambers of the Nitrafixsystem. Alternatively, chamber 20 may sit in the sump. For example, thechamber may be fastened to the edge of the sump by attachment 27. Asshown in FIG. 16, the outlet 23 may be placed on the bottom surface 29of chamber 20, rather than on the side surface, as indicated by thedotted lines. Preferably, chamber 20 should be placed at an elevationwhich is above the water level in the sump so that the water fromchamber 20 may run down into the sump.

Activated carbon, or any other media known in the art which would allowremoval of the hydrogen sulfide gas, could be used in chamber 20.Examples of preferred types of activated carbon for use in the presentinvention are those made from wood or coconut shells. In one embodimentthe activated carbon is Granula Activated Carbon (GAC). The activatedcarbon granules are preferably small in order to provide a high surfacearea. For example, the activated carbon may have an average granule sizeof from ¼ to ⅛ inches or smaller.

Alternatively, the activated carbon system may include multiplechambers. For example, a first wet carbon chamber through which thewater being treated flows may be utilized for removing contaminants,such as hydrogen sulfide gas, from the water. A second dry carbonchamber located above the water level could be used to removeundesirable gaseous emissions. Media other than activated carbon may beused in these systems, as long as the media provides the desiredadsorption of the contaminants to be removed.

Yet another novel processing step 8, which may be added to the Nitrafixprocess, involves the use of algae and bacteria to break down and/orremove unwanted contaminants in the water. This process, which isperformed in a chamber called “the oxytower,” will add oxygen, raise thepH, and remove phosphates, sulfates and remaining nitrates from thewater. A detailed discussion of the oxytower is provided below in thedescription of the preferred embodiments. As shown generally in FIG. 1b, catholyte can be added after step 5, before the water flows into theoxytower.

still another processing step, not shown in FIG. 1 a, may be added tothe process of FIG. 1 a for reducing sulfate and/or hydrogen sulfideconcentrations in aquarium water. This process step utilizes adesulfator, which will be described below in the description of thepreferred embodiments. The process for reducing sulfates may potentiallybe carried out anywhere in the process. For example, the process may becarried out directly after the denitration step 3, or after the calciumstep 5. Catholyte may be added before or after the step of reducingsulfates. While FIG. 1 a indicates that any one of process steps 6, 7and 8 may be used to treat the water, in other embodiments a combinationof these steps may be added to the process in order to achieve thedesired water quality. For example, both an activated carbon chamber anda protein skimmer may be used. In addition, in some applications thewater leaving the denitration chamber can flow directly to an oxytoweror degassing tower and then to the aquarium.

The materials for constructing the systems of the present inventiondescribed in this application, including the chambers and connectingpipes for these systems, are preferably chosen to be safe and non-toxicto aquatic life and are corrosion resistant. Examples of such materialsinclude plastics, such as PVC, polyethylene, polypropylene, methacrylicor acrylic plastic, or fiber glass reinforced plastic (FRP), or metals,such as stainless steel.

PREFERRED EMBODIMENTS

Certain preferred embodiments will now be described. These embodimentsare not to be taken in a limiting sense, but as illustrations of thevarious concepts of the present invention.

FIG. 2 a provides a diagrammatic representation of one embodiment of theNitrafix system for conditioning aquarium water, according to thepresent invention. The Nitrafix system 100, as illustrated in FIG. 2 a,comprises an aerobic bacteria chamber 110, a denitration chamber 120containing anaerobic bacteria, and two chambers, 130 and 140, whichcontain calcium sources. The system may also comprise an additionalchamber 150, which is used as a degassing chamber. As shown in FIG. 2 b,the Nitrafix system can be combined with an external source 160 toprovide catholyte to each chamber in the system.

A detailed description of chambers 110, 120, 130, and 140 of system 100will now be provided with respect to FIGS. 3, 4, 5, and 6, respectively.As shown in FIGS. 3, 4, 5 and 6, each of the chambers is divided intothree separate sections by perforated plates 102 and 103. The topsection 109 of each chamber may be filled with activated carbon, whichis useful for absorbing or removing odorous gases which may be emittedfrom the biological processes occurring within the chambers, such as thehydrogen sulfide gas emitted from the denitration chamber 120. Section108 of each chamber is where the active processes of the system 100occur within each chamber. For example, section 108 is filled with amedia which supports the aerobic and anaerobic bacteria of chambers 110and 120, respectively, and the calcium sources of chambers 130 and 140.The bottom section 107 of each of the chambers is an empty zone, whichallows for improved circulation and dispersion of the water through themedia in section 108.

FIG. 3 illustrates one example of the aerobic bacteria chamber 110 ofsystem 100. Section 108 of chamber 110 may be partially or completelyfilled with a support media 112, which acts as a substrate for theaerobic bacteria. The aerobic bacteria already exist in the water of theaquarium and will readily colonize on the substrate. The media 112 maybe any type of media that can support colonization of aerobic bacteria.While a media having any practical size and shape may be used, mediahaving a high surface area is preferred. For example, sand and othermedia having relatively high surface areas may be used. One form ofsupport media is plastic, preferably in the form of small spheres ortubes, although any shape known in the art may be used. The plasticmedia is lightweight and may float in the aquarium water. It does notclog easily, and provides a large surface area for bacterialcolonization. One example of such a plastic media is known as biofilm.Examples of biofilm which may be used include Kaldnes or Bee-Cell, bothof which are manufactured by Water Management Technologies, Inc. Othermedia like Bio-Chem stars from RENA may also be used.

FIG. 4 illustrates one example of denitration chamber 120, according toan embodiment of the invention. Section 108 of the denitration chamber120 may be filled partially or completely with a media 122 comprisingsulfur, which supports the bacteria used in the anaerobic process.Preferably most or all of the chamber is filled with sulfur, so that thechamber will have a long life. Preferably, the sulfur should have a sizeand shape which maximize surface area, so that more anaerobic bacteriacan live in a given space. In one preferred embodiment, the media maycomprise 90% or more sulfur by weight, and more preferably 99% to 100%sulfur by weight. Thus sulfur preferably has a granular or pastilleshape with a diameter of 3 to 5 mm, although any size and shape known inthe art may be used. This media preferably has a relatively long life inorder to avoid having to frequently replace the media. For example, somemedia known in the art may have a life time of up to 20 years or more.

The chamber, and thus the amount of sulfur and anaerobic bacteria thatcan be held by the chamber, preferably is sized and shaped to containsufficient anaerobic bacteria to reduce the nitrates in the water tosafe levels over an extended period of time, preferably for at least 1to 10 years. The walls of the chamber are preferably opaque. The degreeof reduction of nitrates in the water depends on a number of variables,including the flow rate of water through the chamber, the surface areaof the supported media, the level of nitrates in the water beforeprocessing with the Nitrafix, and the total volume of water to betreated.

Referring to FIGS. 5 and 6, section 108 of calcium reaction chambers 130and 140 may be filled partially or completely with a media comprisingcalcium. Preferably, multiple sources of calcium may be used. Asdiscussed above, examples of calcium media which may be used includecrushed coral, carbonate minerals such as dolomite (CaMg(CO₃)₂), andforms of CaCO₃, such as aragonite and calcite. For example, in oneembodiment, the media is in a gravel form having an average diameter of3 to 5 mm.

As shown in FIG. 5, the portion of section 108 which is nearest to theinlet 131 preferably is filled with dolomite 132, while the portionnearest to the outlet 134 is filled with aragonite media 133. Water fromthe denitration chamber first flows through the dolomite media, whichhas a rate of solubilization that is slower than that of aragonite. Asthe water flows over the dolomite, the pH of the water is raised (i.e.,the acidity of the water is decreased). The water having decreasedacidity then flows through the faster solubilizing aragonite media,which results in the aragonite media being dissolved more slowly than ifit had been dissolved in the more acidic water entering chamber 130. Inthis manner the longevity of the media in the calcium chamber isincreased and a desirable mineral content for the water is achieved.

FIG. 6 illustrates one example of an arrangement of calcium media whichmay be used in reaction chamber 140. Section 108 of chamber 140 isfilled with calcite 142, which is surrounded by crushed coral 143. Inone embodiment, the calcite media may be in the form of sand, which iscontained in a water permeable bag. This arrangement has the benefit ofpreventing clogs in the chamber, since the water can easily circulatethrough the crushed coral surrounding the calcite. The calcite isbeneficial for aquariums containing coral, algae, and invertebrateanimals, which use calcite to make their skeletons and/or shells. In analternative embodiment (not shown) for chamber 140, a calcium mediafills the lower portion of section 108, while activated carbon is placedin the top portion of section 108. The activated carbon in section 109remains dry, while water flows through the activated carbon in section108. In this embodiment, the activated carbon in section 109 reduceshydrogen sulfide gas emissions removed from the water by the activatedcarbon in section 108, as described above with respect to the activatedcarbon chamber of FIG. 16. The volume of activated carbon in section 108may be approximately equal to the volume of dry activated carbon insection 109, although the amounts in either section may be optimized toprovide the desired contact time between the activated carbon and eitherthe water in section 108 or the emissions in section 109, in order toobtain the desired benefits of the activated carbon.

In general applications, sulfur used in the denitration chambers mayhave a useful life within the range of 20 years, while the calcium whenplaced in the preferred embodiment may have a life of about 1 to 5years. In general, media having longer life times is preferable in orderto increase the time period between media replacements. In largerapplications, at least certain components and materials, such as sulfur,calcium, and other media, etc. need to be periodically replaced orcleaned.

As discussed above, in one embodiment, a degassing chamber 150 is addedto the biological system 100, as illustrated in FIG. 2 a. While thedegassing chamber 150 may be used for smaller aquariums, it is moreoften used for larger aquariums. Any conventional degassing systems,such as those discussed above, may be used as the degassing chamber 150.In an alternative embodiment, the activated carbon chamber of FIG. 16 orthe oxytower of FIG. 18 a, is used in place of degassing chamber 150.

Water may be forced through the chambers using any workable arrangement.In one embodiment, as can be seen from the flow arrangements of FIG. 2a, water flows through aerobic chamber 110 from top to bottom, while thedirection of flow in chambers 120, 130 and 140 is from bottom to top. Aflow rate from the bottom to the top in all, or at least chambers 120,130, and 140, is preferred because such a flow helps prevent clogs inthese chambers and allows gases formed in the chambers to better escapethrough the tops of the chambers. The chamber covers preferably areperforated so as to allow the gases to escape. In one embodiment, theflow through degassing chamber 150 is from top to bottom, as shown inFIG. 2 a.

The chambers of the biological system 100 may have any workable shape,such as a cylindrical or box shape. The size of the chambers may alsovary according to the requirements of the aquarium.

Another preferred embodiment of the present invention is illustrated inFIGS. 8 a to 8 c. A three dimensional view of this system is shown inFIG. 14. This embodiment is similar to that of system 100, illustratedin FIG. 2 a, except that it has been modified so that all of thechambers are contained within a single integral unit to provide for acompact system design. Further, in the illustrated embodiment, all ofthe chambers have the same shape and size, but respective chambers canbe sized differently, as circumstances require. All of the chambers ofthe FIG. 8 embodiment may fit into a single cubic shaped container, asillustrated in FIG. 14.

FIG. 8 a illustrates a top view of an embodiment of a system whereinaerobic chamber 110, denitration chamber 120, and calcium chambers 130and 140 are each arranged within a single container. As shown in FIG. 8b, water flows into the system through inlet 101, which comprises a gatevalve 101 a, which allows for control of the flow rate of water throughthe system. Other types of valves, such as a needle valve, may also beused. Inlet 101 also includes a clear section of conduit 101 b, whichallows visual inspection of the water flow so that clogging may bedetected. Both inlet 101 and outlet 141 may comprise, for example, PVCpipe which is ½ inch in diameter.

The water flowing into the system flows down through aerobic chamber 110and enters near the bottom of chamber 120 through an opening in section109. The water then flows up through the sulfur media in section 108 ofdenitration chamber 120. The water exits chamber 120 near the top ofsection 108 and flows straight across into the top of section 108 ofchamber 130 through openings 121 in the chamber wall, so that the waterflows from top to bottom in calcium chamber 130. This flow arrangementallows for a more compact design than the flow arrangement illustratedin FIG. 2 a, in which the water in chamber 130 flows from bottom to top.

The water flowing from calcium chamber 130 enters the second calciumchamber 140 near the bottom of section 109, flows up through the mediaof section 108, and exits the system through outlet 141. Outlet 141 alsocomprises an overflow elbow 141 b with a clear section of conduit 141 a,which allows for visual inspection to determine if the system isoverflowing. Multiple openings, as illustrated by openings 121 in FIGS.8 b and 8 c, may also be used to allow water to flow between chambers110 and 120 and chambers 130 and 140. Vents 150 may be placed in thecoverings 104 of the chambers to allow gases produced in the chambers toescape from the system. Vents 151 may also be placed between adjacentchambers which allows gas flow between the upper sections 107 of eachchamber containing activated carbon.

In one embodiment, a section of tubing is used to connect a vent (notshown) with one of the vents 150 in order to equalize the pressurebetween the inlet and the Nitrafix chambers. This helps to ensure thatthe level of water in the clear plastic tube 101 b accurately reflectsthe level of water in the Nitrafix. When water is flowing through theNitrafix system properly, the level of water in the clear tube 101 bshould be at about the same level as the outlet 141. If the level ofwater in tube 101 b is lower than the outlet 141, an air bubble may beformed in the outlet tube, or the system may be clogged. If the water isflowing through the clear elbow 141 a above the outlet on the outletside, then the system is overflowing.

As discussed above, section 108 of each of the chambers 110, 120, 130and 140 of the embodiment of FIG. 8 may respectively contain the samemedia as described above for chambers 110, 120, 130 and 140 of theembodiment illustrated in FIGS. 2 to 6. However, in another preferredembodiment, the upper portion of section 108 of chamber 140 of the FIG.8 embodiment may be filled with activated carbon, while the lowerportion of section 108 may be filled with calcium, such as the crushedcoral and calcite sand arrangement illustrated in FIG. 6 a. The volumeof activated carbon in section 108 may be approximately equal to thevolume of dry activated carbon in section 109, although the amounts ineither section may be optimized to provide the desired contact timebetween the activated carbon and either the water in section 108 or theemissions in section 109, in order to obtain the desired benefits of theactivated carbon. In this manner, the benefits of running the waterthrough the activated carbon, such as degassing, may be realized, whilestill allowing the system of FIG. 8 to remain compact. Sections 107 ofthe chambers in the FIG. 8 embodiment may also contain dry activatedcarbon and sections 109 may remain empty, as described above for theembodiment illustrated in FIGS. 2 a to 6.

The container for the Nitrafix of FIGS. 8 a to 8 c may be made of anyappropriate material known in the art. In one embodiment, the materialis ¼ inch plastic. Other materials, such as PVC, polyethylene,polypropylene, methacrylic or acrylic plastic, or fiber glass reinforcedplastic (FRP), or stainless steel, can also be used. Since the anaerobicbacteria are more efficient at removing nitrates in a dark environment,the container preferably is opaque, so as not to let light through. Forexample, the container may be a black acrylic plastic.

The size of the FIG. 8 embodiments may be adjusted as appropriate fortreating any size aquarium. For example, aquariums of up to 5000 gallonsor more may be treated. In one embodiment, known as the N-500, thecontainer in FIG. 8 has a width of 14 inches, a depth of 14 inches, anda height of 20 inches, and is used to treat aquariums holdingapproximately 10 to 500 gallons.

The ratio of chamber height to chamber volume may be adjusted in orderto control the amount of time the water maintains contact with a givenvolume of media within each chamber, as well as the volume (and thus thesurface area) of media within the chamber. A longer contact time and/ora greater surface area of the media within the chamber can allow formore efficient processing for any given volume of media and/or a fasterprocessing time for a given flow rate of water through the chamber. Inone embodiment of FIG. 7, the height H2 of section 108 of the chamber is3 to 5 times L, where L is the diameter of the chamber for a cylindricalchamber, or the width of the chamber for a cubic or box shaped chamber.The heights, H1 and H3 of sections 109 and 107, respectively, can be anyheight. In one embodiment, H1 and H3 are each chosen to have a height ofat least ⅛ the height of H2.

The specifications for the systems of the present invention, such as thedimensions of the chambers, the volume of media to be used, and the flowrate through the system, will depend on certain parameters. Theseparameters include, for example, the starting pH and nitrate level ofthe aquarium to be treated, the fish load and amount of feed added tothe aquarium, as well as the desired pH and nitrate levels for theaquarium. Given the necessary parameters, the optimum specifications foreach of the systems of the present invention, as described herein, canbe determined through experiments and testing, as a particular device orsystem is being developed under the principles of the invention, toapply to a particular application.

In order to help determine the optimum specifications when designing aNitrafix system, the following formulae may be used for calculating theflow rate through the system, volume of media in each of the chambers ofthe system, and the time for treating 99.99% of water in a recirculatingsystem.

The desired flow rate can be determined according to the formula I,F=V _(t) /A  (I)where

-   -   F is flow rate in gallons per hour,    -   V_(t) is the volume of water (in gallons) in the aquarium to be        treated per hour, and    -   A is an experimentally determined coefficient having a value        which depends on a number of variables, including the nitrate        level of the water, the quality of the filtration, and the        volume of water to be treated. The greater the nitrate level,        the greater the value for A. The value of A may range, for        example, from 30 to 200. To simplify the calculations and avoid        experimentation, a value of 100 may be used for aquariums having        a volume of water of under 10,000 gallons, although the value        for A may be determined experimentally if greater precision is        desired. Generally speaking, larger systems may have values        lower than 100, such as from 20 to 50, although the exact value        for these larger systems will generally be determined        experimentally.

The volume of media in section 108 of each of the chambers may becalculated according to formula II,V _(m) =V _(t) /N  (II)where

-   -   V_(m) is volume of media in the chambers    -   V_(t) is volume of water in the aquarium to be treated    -   N is an experimentally determined coefficient having a value of        from 100 to 500, depending on the volume of water to be treated        (V_(t)) and the amount of food added to the tank, or TAN. For a        typical fish tank up to 10,000 gallons, N may be chosen to        be 200. The value for N may increase for larger aquariums or for        aquariums with fewer fish. The value for N may decrease for        aquariums with large numbers of fish.

In one example, nitrates are calculated to be reduced in saltwater byapproximately 100 ppm in one cycle using a pastille shaped sulfur mediahaving a surface area of 11.36 cm²/g, and a volume of media calculatedusing a value of N=400, which was randomly chosen for the purpose ofthis example.

The formula for determining the time it would take to treat 99.99% ofthe water in a recirculating system (i.e., the length of time per cycle)is determined byT=9.2 V _(t) /F _(o)where

-   -   T is the amount of time per cycle (in hours),    -   V_(t) is the volume to be treated in gallons, and    -   F_(o) is the flow through the sulfur in gal/hour.

Before the water being treated by the embodiments of FIG. 8 is returnedto the aquarium tank, it is preferable to add oxygen to the water,especially for large aquariums of, for example, 10,000 gallons or more.In one embodiment, a degassing chamber, such as a protein skimmer orother conventional degassing chamber, is used to accomplish this. Oneexample of a novel protein skimmer which may be used will be discussedbelow in the description of FIGS. 20 a to 22 b. In an alternativeembodiment, the oxytower, as discussed above, is also used to add oxygento the water.

Another preferred embodiment is illustrated in FIG. 15, which shows asystem comprising multiple sections arranged vertically through a singlechamber 500. The sections are separated by perforated plates 503.Section 510 is an empty space through which water entering the chambercan flow. Section 520 contains a media capable of supporting aerobicbacteria, such as the aerobic bacteria previously described herein.Section 530 contains sulfur media capable of supporting anaerobicbacteria, such as the anaerobic bacteria previously described. Sections540 and 550 both contain calcium media. The calcium media in section540, which is the calcium chamber nearest the inlet, contains arelatively less soluble media compared to the calcium media contained insection 550. Both sections 560 and 580 preferably contain activatedcarbon media, which traps undesirable contaminants, such as hydrogensulfide gases, which may be produced during the process. Section 570 isleft empty to allow for easy flow of water out of the system 500.

Water flows through inlet 516 down pipe 513 and through pipe 501, upthrough system 500 and exits through pipe 511. Exhaust gases generatedduring the process can exit system 500 through exhaust vent 550. Tubing517, extending up from exhaust vent 550, may optionally be used to raisethe level to which the water must rise before overflowing out of thesystem. A portion of clear pipe is preferably used to allow for visualinspection of the system. For example, clear pipe section 513 and/orclear pipe section 514, as illustrated in FIG. 15, may be used toconnect the inlet pipe 501 and the exhaust pipe 550 to either end of a Tpipe junction 516. Generally, any type of clear pipe may be used. Forexample, glass or clear plastic, such as clear PVC, may be used for theclear pipe sections. The upward flow of water through system 500 helpsto prevent clogging.

The dimensions of the chamber 500 can vary according to the requirementsof the aquarium. The chamber 500 may have, for example, a cylindricalshape. In one embodiment, chamber 500 is a PVC pipe having a diameter ofapproximately 4 inches and a length of approximately 20 inches, witheach section having the following approximate lengths:

-   -   Empty space, section 510—1.5 inches    -   Media for aerobic bacteria, section 520—2.5 inches    -   Sulfur media, section 530—4 inches    -   Hard calcium media, section 540—3 inches    -   Soft calcium media, section 550—3 inches    -   Activated carbon media, section 560—2.5 inches    -   Empty space, section 570—1.5 inches    -   Activated carbon, section 580—2 inches.        The total weight of this 20 inch embodiment is approximately 12        pounds. It can be used for an aquarium having a volume of up to        about 120 gallons of water. In certain applications, this        embodiment can be a disposable unit that can be thrown away. In        other applications, the media in the system can be replaced as        needed. The diameter and length of the chamber and the lengths        of the sections 510 to 580 could be increased or decreased, as        desired, in order to treat larger or smaller aquariums.

FIG. 12 a illustrates another embodiment of the present invention. Asshown in FIG. 12 a, the system comprises a biological system 400comprising an outside container 402 divided into various chambers orcartridges, as illustrated by perforated walls 403. The outsidecontainer may be made of a plastic material, such as acrylic, forexample. The material may be opaque, such as black colored plastic. Thechambers containing the media may also be made of plastic, such aspolyethylene or polypropylene.

system 400 is generally for use with smaller aquariums, such as thosehaving 5 to 50 gallon tanks. However, it may be used for larger systems,as well. It is designed to hang on the aquarium tank wall, having bothan inlet 401 and an outlet 411, which extend over the tank wall and downinto the aquarium, as shown in FIG. 13. For residential aquariums, asystem according to this embodiment is configured in a disposable unitthat can be purchased in a closed configuration with all of the elementsand components in the unit. Such disposable units may have a life in therange of about 1 to 2 years, for example, depending on the life of themedia used therein.

The denitration chamber 420 is filled with a sulfur media, such as anyof the sulfur media previously described above. Calcium chamber 430 isfilled with one or more calcium sources, such as any of the calciumsources described above. In a preferred embodiment, chamber 430 isfilled with a mixture of aragonite, dolomite and calcite. Alternatively,the chamber may be filled with only one or two of these sources ofcalcium, rather than all three. The denitration chamber 420 and calciumchamber 430 function to remove nitrates, add calcium and control pH,similar to the denitration chamber and calcium chambers of the abovedescribed embodiments.

In one embodiment, both chambers 410 and 440 remain substantially empty,except for the flow of aquarium water. Water flows into chamber 410through inlet 401. Water then flows from chamber to chamber throughperforated walls 403, first flowing through denitration chamber 420,calcium chamber 430, and then into chamber 440. In order to force waterthrough the system, air is pumped through air hose 460 into outletconduit 411, which extends down into chamber 440. The air bubbles risingup through outlet conduit 411 force water up and out of the system.Other systems known in the art for moving water through system 400 maybe used instead of the air pump, such as, a minni-pump, for example.

Chamber 407 is filled with activated carbon, which acts to removehydrogen sulfide gas odors produced in the denitration chamber. Gasesemitted from the system can rise through the perforated plates 404 andleave the system through vents 450.

Another embodiment is shown in FIG. 12 b. This embodiment is similar tothe embodiment described above for FIG. 12 a, except that a chamber 415,which is filled with a media for supporting aerobic bacteria, is addedbetween chambers 410 and 420. The media in chamber 415 may be any mediacapable of supporting aerobic bacteria, such as, for example, crushedcoral or biofilm. This purpose of chamber 415 is to remove oxygen andreduce ammonia to nitrite and nitrite to nitrate, similar as describedabove with respect to the aerobic chamber 110 for the embodiment ofFIGS. 2 a and 8.

Another embodiment of the present invention is the application of theinvention to large fresh and salt water aquariums having a volume of,for example, 10,000 gallons or more. As with the other Nitrafix systemsdisclosed herein, this embodiment of the invention is applicable to bothfresh and salt water aquariums, as well as brackish water aquariums, andmakes it possible to create a working salt water aquarium in an inlandlocation that does not have another available source to replace all orpart of the salt water in the aquarium, as is done under standardsystems for large salt water aquariums. Such a system is shown generallyin FIG. 17 a.

As shown generally in FIG. 17 b, catholyte can be added to a Nitrafixsystem for use with large aquariums. In a preferred embodiment, thecatholyte is produced on site by a device 690 that creates catholyte andanolyte from water in an electrochemical process. The supply of freshlyproduced catholyte is applied directly from machine 690 or a holdingtank to the system.

As shown in FIGS. 17 a and b, water from the aquarium is first suppliedto a chamber 610 that supports the colonization of aerobic bacteria thatreduce ammonia and nitrites in the water and increase concentrations ofnitrates. For example, a sand filter or a floating bed reactor filter,both of which are well known in the art, may be used as chamber 610.Examples of specific sand and floating bed filters which may be usedinclude a bead filter, from aquaculture systems technologies, and sandfilters from Jacuzzi. These filters would both filter out unwantedmaterial from the water and also support the aerobic process of reducingammonia and nitrites in the water while increasing nitrates and at thesame time increasing CO₂ concentrations and reducing or eliminatingdissolved oxygen in the water. As previously explained, the aerobicbacteria chamber will increase the efficiency of the denitration processby the anaerobic bacteria and reduce the amount of bacteria and sulfurneeded in the second chamber.

One embodiment of a novel aerobic chamber for use in the systems ofFIGS. 17 a and 17 b will now be described with reference to FIG. 24.Chamber 610 comprises a tank 108. The lower portion of tank 108preferably has a tapered shape to collect sediment which settles to thebottom, although it may have a flat bottom. A drain 326 a and valve 326b can be included in the bottom of 610, to allow sediment to beperiodically removed. If desired, a clear section of pipe 326 c may beemployed to allow visual inspection of the drain so that sedimentbuildup may be monitored.

A lid 106 may be used to cover the tank 108. Chamber 610 should berelatively air tight, so that the level of oxygen in the water mayeffectively be reduced by the aerobic bacteria. A vent 113 having acheck valve 114 is used to vent gases from the chamber, but willpreferably not allow substantial amounts of outside air into thechamber.

The chamber has an inlet 111 and an outlet 121 through which water canenter and exit the chamber. A screen 101 is preferably placed over theoutlet and inlet to avoid clogging and contain the media within thechamber. The height H1 of the inlet pipe 111 a will control the level ofwater in chamber 610. In one embodiment, catholyte can be added to theaerobic chamber. The catholyte is provided from an external source asshown generally in FIG. 17 b, and may be added to the chamber by anymeans known in the art. Preferably, the catholyte is added by drippingthe solution into the water as it flows through inlet 111, before itenters chamber 610. The catholyte is added in an amount that ranges fromabout 1 to about 20 percent of the total volume of water flowing throughthe system.

section 108 of chamber 610 may be partially or completely filled withsupport media 112, which acts as a substrate for the aerobic bacteria.The aerobic bacteria already exist in the water of the aquarium and willreadily colonize on the media. The media 112 may be any type of mediathat can support colonization of aerobic bacteria. While a media havingany practical size and shape may be used, media having a high surfacearea is preferred. For example, sand, crushed coral and other mediahaving relatively high surface areas may be used. One preferred form ofsupport media is plastic, which may be in the form of small spheres ortubes, although any shape known in the art may be used. The plasticmedia is lightweight and may float in the aquarium water. It does notclog easily, and provides a large surface area for bacterialcolonization. One example of such a plastic media is known as biofilm.One particular type of biofilm is manufactured by Water ManagementTechnologies, Inc. under the name of Kaldnes or Bee-Cell. Other medialike Bio-Chem stars from RENA may also be used. In one embodiment, whenmedia 112 does not float, a perforated plate or screen 115 is employedto hold the media above the cone shaped bottom, to allow a space forsediment to settle in the tank.

As shown in FIGS. 17 a and 17 b, the system preferably includes aplurality of anaerobic denitration chambers 620 which are placed inparallel flow with each other. Alternatively, the chambers may be placedin series, where water flows from one denitration chamber to the next.Each chamber might, for example, be a cylindrical chamber having adiameter ranging from about 6 inches to about 10 feet and height rangingfrom about 8 to about 20 feet. The chamber may be sized so that it canbe readily positioned in the basement of the aquarium facility, or atsome other acceptable location. These chambers can be placed indifferent locations relative to the aquarium, even including locationssignificantly remote from the aquarium itself. As the applicationpreviously explained, anaerobic bacteria within the chambers reducenitrate concentrations.

Preferably the denitration chambers either include a degassing material,or provide an outlet for allowing exhaust gases produced during thedenitration process to flow to a separate chamber containing degassingmaterial, in order to eliminate the odor from noxious gases, such ashydrogen sulfide, which may be produced during the denitration process.The degassing material may be, for example, activated carbon.

In one embodiment, catholyte is added to the denitration chambers. Thecatholyte is provided from an external source as shown generally in FIG.17 b, and may be added to the chamber by any means known in the art.Preferably, the catholyte is added by dripping the solution into thewater as it flows through the inlet before it enters chamber 620. Thecatholyte is added in an amount that ranges from about 1 to about 20percent of the total volume of water flowing through the system.

Examples of denitration chambers that may be used for large aquariumsare illustrated in FIGS. 9 and 11 and will now be described. Where largeamounts of sulfur media are used to treat the aquarium water, the sulfurmay crush itself by its own weight in the lower parts of the chamber andcause clogging. In order to avoid clogging, as well as to increase theefficiency of the biological system, a denitration chamber 220 accordingto an embodiment illustrated in FIG. 9 may be used. As shown in FIG. 9,the sulfur media 122 is placed on shelves 223 within the chamber. Theshelves are perforated in order to allow water to flow through thechamber. The chamber bottom 225 has a tapered shape to collect sediment.A drain 326 a and valve 326 b can be included in the bottom of chamber120, to allow sediment to be periodically removed. If desired, a clearsection of pipe 326 c may be employed to allow visual inspection of thedrain so that sediment buildup may be monitored. The chamber has aninlet 211 and an outlet 221 through which water can enter and exit thechamber.

FIG. 11 illustrates another denitration chamber embodiment, whichutilizes floating balls comprising sulfur. FIG. 10 shows a floating ball322 comprising sulfur, according to one embodiment of the presentinvention. The balls have a density that is less than that of water, andtherefore float in the water. The balls may be hollow plastic orStyrofoam balls which are filled with a mix of sulfur media and plasticor Styrofoam media. Holes 323 in the balls allow water to flow into andout of the balls and contact the sulfur media contained therein. Theballs and the media contained in the balls may be any workable size orshape. For example, in one embodiment, the balls have a diameter of 1½to 3 inches with ⅛ to 5/32 inch diameter holes drilled therein, and themedia within the balls has a diameter of, for example, ⅛ inch to ¼ inch.

The floating balls comprising sulfur are placed in a chamber, such aschamber 320 illustrated in FIG. 11, for example. The chamber shown inFIG. 11 is a cylinder having a conical shaped bottom 325, in order tocollect sediment. Clear tubing 326 may be placed at the tip of thechamber bottom 325 in order to allow for visual observation of sedimentwhich may be collected. Valve 327 allows the sediment to be drained fromthe chamber bottom when necessary. Chamber 320 may be made of, forexample, PVC, polyethylene, polypropylene, methacrylic or acrylicplastic, fiber glass reinforced plastic (FRP), or stainless steel. Inone embodiment, an inlet 311 is placed near the bottom of the chamberand outlet 321 near the top, so that the aquarium water flows up thoughthe sulfur containing media and exits the chamber through outlet 321. Agas outlet 324 is placed in the top of chamber 320 to allow gasesproduced in the chamber to escape. The exhaust gases may then be flowedthrough activated carbon, in order to remove hydrogen sulfide gas,before being released into the atmosphere.

Chamber 320 is filled with the floating sulfur media. In a preferredembodiment, ½ to ¾ of the volume of the tank is filled with the floatingsulfur balls 322. In certain embodiments, the balls may be washed duringthe operation of the chamber. In the embodiment of FIG. 11, for example,a backwash pump 328, which pumps water out of the chamber and thenreturns it to the chamber through a conduit having an outlet in closeproximity to the floating balls, is used to wash the balls. In analternative embodimet, an injector (not shown) may be used to injectcarbon dioxide gas into the chamber to wash the balls. Washing the ballshelps remove any particulate matter that can build up on or between theballs. Such build up can undesirably reduce the flow of water throughthe holes in the balls, as well as through the chamber itself.Additionally, the backwash pump or injector may increase contact timebetween the sulfur surface area of the balls and the water being treatedby increasing the circulation of balls inside the chamber. Additionally,the motion of the balls caused by the backwash pump or injector may helpgases that form inside the balls during the process to be discharged,which allows more water to enter the balls, thus increasing contact timeof the sulfur with the water.

After denitration occurs in the system disclosed in FIGS. 17 a and 17 b,water can then be directed to flow through one or more calcium chambers630 or other chambers or systems to increase the pH of the water and addappropriate minerals for the health of sea life and coral within theaquarium. As shown in FIG. 17 b, catholyte can be added to the water asit flows to the calcium chambers or other systems.

One embodiment of a calcium chamber for large aquariums is shown in FIG.25. Where large amounts of calcium media are used to treat the aquariumwater, the calcium may crush itself by its own weight in the lower partsof the chamber and cause clogging. In order to avoid clogging, as wellas to increase the efficiency of the system, a calcium chamber 630according to an embodiment illustrated in FIG. 25 is used. As shown inFIG. 25, the calcium media 632 is placed on shelves 633 within thechamber. Various sources of calcium may be used, such as aragonite,calcite and dolomite, as described above in connection with the otherembodiments of the Nitrafix. If multiple sources of calcium are used, itis preferable to place the harder to dissolve calcium on the bottomshelves and the more easily dissolved calcium on the upper shelves, inorder to extend the life of the calcium media. The size of the media maybe any practical size known in the art. For example, the size may rangefrom 3 to 10 mm in diameter.

The shelves are perforated in order to allow water to flow through thechamber. The chamber bottom 635 preferably has a tapered shape tocollect sediment and small particles of calcium which fall through theperforations in shelves 633, although it may have a flat bottom. A drain326 a and valve 326 b can be included in the bottom of chamber 630, toallow sediment and calcium to be periodically removed. If desired, aclear section of pipe 326 c may be employed to allow visual inspectionof the drain so that sediment buildup may be monitored. The chamber hasan inlet 631 and an outlet 641 through which water can enter and exitthe chamber. A lid 636 may be used to cover the chamber, and may containa vent having a check valve to vent gases from the chamber.

In one embodiment, catholyte is added to the calcium chamber by drippingcatholyte into the water as it flows through inlet 631 before it enterschamber 630. The catholyte is added in an amount, for example, thatranges from about 1 to about 20 percent of the total volume of the waterflowing through the system.

Other embodiments are also useful for large aquariums. For example,water from the denitration chambers can be directed to one or more ofthe following systems, in addition to or in place of a calcium chamberor chambers: a protein skimmer 650, a degassing tower 660, an oxytower670, and a desulfator 680. While protein skimmer 650, degassing tower660, oxytower 670, and desulfator 680, are being described here inconnection with the embodiment of FIG. 17 a and 17 b for use with largeaquariums, they are also contemplated for use with aquariums of anysize, including home aquariums of 50 gallons or less.

A novel protein skimmer will now be described in connection with FIGS.20 a to 20 e. The purpose of the protein skimmer is to removecontaminants, such as undesirable organic matter, otherwise known asdissolved organic compounds (DOC), from the water, as well as toincrease the oxygen level of the water. Protein skimmer 650, as shown inFIG. 20 a, includes a mixing chamber 651, a collecting cup 652, a mixingeductor 653, and a bowl shaped cup 655. The protein skimmer of FIG. 20 ais preferably used for salt water applications where the water has aspecific gravity greater than about 1.020, although it may also be usedfor fresh water applications.

Water flows into mixing chamber 651, which remains substantially filledwith water during processing, through inlet 654. The water in the mixingchamber is circulated using pump 656, which draws water from the chamber651 through pipe 658 and forces the water through eductor inlet channel653 a. Alternatively, the water going to eductor inlet channel 653 acould be supplied from a source outside chamber 651, such as from thesump or the aquarium itself. Water passing through the eductor mixingchannel 653 b is mixed with an oxygen-containing gas, such as air,oxygen gas, ozone, ionized gas, or a mixture thereof. Using ozone willmake the system more efficient and reduce or eliminate sulfate. Theoxygenated stream of water, having bubbles comprised of theoxygen-containing gas, flows out of the eductor and down into chamber651 against concave surface 655. Concave surface 655, which may have cupor bowl shape, then redirects the stream of water and bubbles upwardinto the mixing chamber. As the bubbles rise in the chamber, undesirablecontaminants attach to the bubbles and rise to the surface, where theyare captured in the collecting cup 652 and disposed of. The eductor 653allows for a relatively large amount of gas to be mixed into a liquidusing a relatively small amount of power. An enlarged view of eductor653 is shown in FIG. 21 a. The mixing channel 653 b comprises a flaredinlet region 653 f and a flared outlet region 653 g, which are connectedby a generally cylindrical shaped neck region 653 e.

The inlet channel 653 a of the eductor, which may be, for example, anozzle, is located near the flared inlet of the mixing channel 653 b, sothat a central longitudinal axis of the inlet channel 653 a is alignedalong the central longitudinal axis of the mixing channel 653 b, in amanner which allows water from the chamber 651 to be entrained throughthe opening 653 d between the outside of the inlet channel and theinside of the flared inlet region of the mixing channel. To beefficient, the stream of water from inlet 653 a preferably entrains arelatively large amount of water from chamber 651 as it flows intomixing channel 653 b, so that the flow of water through the channel 653b is significantly greater than the flow from inlet 653 a. For example,as illustrated in FIG. 21 b, the flowrate “B” of water entrained may be3 to 6 times greater, and is preferably 4 times greater, than theflowrate “A” from inlet 653 a. The flowrate of water exiting the eductoris thus “A”+“B.” In this manner, the use of the eductor in the proteinskimmer allows for a relatively large volume of water to be mixed withgas utilizing a relatively small amount of power.

Additionally, the use of the eductor will increase the contact timebetween the gas bubbles and the liquid by providing improved mixing ofthe bubbles with the water, which may allow the skimmer of the presentinvention to be smaller and more efficient than conventional proteinskimmers.

As shown in FIG. 21 b, the tubing 653 c is positioned in the flow ofwater through channel 653 b at an angle θ_(t) from the centrallongitudinal axis of channel 653 b. Adjusting the angle θ_(t) has beenfound to provide for improved entrainment and mixing of the gas with thewater. While the angle θ_(t) may range, for example, from 0 to 90°,θ_(t) preferably ranges from 30 to 60°, and is more preferably about45°.The angle of the tube opening θ_(o), as illustrated in FIG. 21 b,may also be adjusted to provide for improved entrainment. For example,the angle θ_(o) may be adjusted from 90° to 135°. The tubing extendsinto the flow path of the mixing chamber, preferably so that the outletof tubing 653 c is preferably located at or near the centrallongitudinal axis of the mixing channel 653 b. The diameter of thetubing may be adjusted to allow more or less gas into the mixingchannel, without undesirably interfering with the flow through thechannel. For example, the tubing may have a diameter ranging from ⅛ inchto 1 inch. The water flowing past the tubing 653 c creates a suction,thus causing the fluid in tubing 653 c to be sucked from the tubing andinto the mixing channel 653 b.

In one embodiment, shown in FIG. 21 d, tubing with two differentdiameters is used to allow for a larger amount of gas to flow into themixture, without interfering with the flow through the mixing channel.As shown in FIG. 21 d, tubing 653 i connects in an airtight manner totubing 653 c of the jet mixers, so that the gas flowing from the gassource towards the mixing eductor through tube 653 i will flow throughtube 653 c and into the mixing channel. The diameter D of tubing 653 imay range from 1 to 10 times the diameter d of tubing 653 c. In oneembodiment, D ranges from 3 to 4 times d. For example, in oneembodiment, the diameter d may range from ⅛ inch to 1 inch, whilediameter D has a diameter greater than 1 inch. The larger diameter D oftubing 653 i relative to the diameter d of tubing 653 c allows for anincreased gas flow to the jet mixers and consequently an increasedvolume of gas bubbles introduced into the water in the tank.

The mixing eductor, including the nozzle, mixing chamber and tubing maybe made of various materials, such as plastic or metal. Specificexamples of such materials include PVC, polyethylene, polypropylene,methacrylic or acrylic plastic, fiber glass reinforced plastic (FRP), orstainless steel. Any other materials, known in the art for makingeductors, may also be used. The mixing eductor is contemplated for usein other applications. For example, rather than a gas, a liquid may beflowed through tubing 653 c, so that multiple liquids may be mixedtogether. Additionally, more than one tube 653 c may be positioned inthe mixing channel. For example, mixing eductors having two, three, fouror more tubes positioned in the mixing channel in a manner similar totube 653 c are contemplated. A three dimensional view of an embodimentof the eductor is illustrated by FIG. 21 c.

Another embodiment of the protein skimmer, which is preferably used forfresh water applications, is shown in FIG. 20 b. This embodiment issimilar to the embodiment of FIG. 20 a, as described above, except forthe dimensions of the eductor, and the concaved surface 655. As shown inFIG. 20 b, the length of the outlet cone 653 g is longer than theeductor used in the embodiment of FIG. 20 a, and may range, for example,from about 1 inch to about 80 inches long, and may more preferably befrom about 20 to about 60 inches long. In addition, the angle, θ_(f), ofthe outlet cone may be adjusted so that the cone encompasses arelatively large volume of water in the chamber. For example, the angle,θ_(f), may range from about 1° to about 60°, and may more preferably befrom about 30° to about 45°. The larger cone acts to trap gas bubbles,which are forced upward by the concave surface 655, so that the bubblesare not allowed to rise to the surface, but remain trapped between thecone and the surface 655, where the water is well mixed and the bubbleswill be forced to circulate through the water. This increases thecontact time of the bubbles with the water before they finally escapefrom underneath the cone, thereby increasing the amount of organicmatter trapped by the bubbles. If necessary, the size and shape of theconcave surface 655 may also be adjusted to reduce the space “L” betweenthe surface 655 and the end of cone 653 g, in order to more effectivelytrap the bubbles underneath the cone. For example, L may range fromabout ¼ inch to about 60 feet, and may more preferably be from about 8inches to about 10 feet.

The longer contact time is especially important for fresh water, as thebubbles formed in fresh water are naturally smaller than the bubblesformed by the eductor in salt water, which effectively decreases thetotal surface area of the bubbles formed in fresh water, thus decreasingthe efficiency of the skimmer. This difference in bubble size is thoughtto be caused by the different specific gravities of salt and freshwater. In any case, the increased contact time of the bubbles in theFIG. 20 b application helps to compensate for the decrease in totalsurface area of the bubbles in fresh water. However, the embodiment ofFIG. 20 b is not limited to fresh water, but may be used any timeincreased contact time between the bubbles and the water is desired.

In yet another embodiment, illustrated in FIGS. 22 a and 22 b, theoutlet cone 653 b of the eductor is modified by adding wings, or foils,653 d to the inner surface of the outlet cone. The foils rotate aroundthe inside surface of the outlet cone in a manner which act to directthe motion of the water through the cone in a helical path, thuscreating a vortex. Such a circular motion may act to increase thecontact time of the bubbles with the water, and thereby increase theefficiency of removal of organic matter in the water. The dimensions ofthe foils may be modified to be any size or shape which will create thedesired circular motion. For example, the foils may extend from about1/16 to about 1 inch from the inner surface of the cone for the entirelength, or only a portion of the length, of the outlet cone 653 d, andmay have a width of from about 1/32 to about ⅛ inches.

A preferred embodiment for a protein skimmer is shown in FIG. 20 d. Inthis embodiment, the portion of inlet 654 that leads into the tank ispositioned to direct the flow of water along the side of the tank in amanner which induces a downward circular flow of the water inside theskimmer. This downward circular flow creates resistance against thenormal directional flow of the bubbles rising out of the eductor, andtherefore increases contact time between the water and bubbles. Thisembodiment can also be used in conjunction with other features discussedfor the skimmer, including the optional cone of FIG. 20 b.

Embodiments using multiple eductors in a single tank are alsocontemplated, as shown in FIG. 20 c. The eductors may be arranged bothvertically and/or horizontally within a tank in order to provide thedesired circulation of bubbles for any given shape or size of tank, tomaximize removal of organic matter.

While the novel protein skimmers described above for use in the systemfor large aquariums, as illustrated by FIGS. 17 a and 17 b, the proteinskimmers of the present invention may be used in any system where aprotein skimmer is desired. For example, the protein skimmers of thepresent invention may be used in combination with any of the otherNitrafix systems disclosed herein. The flow through the protein skimmermay be optimized to achieve the desired water quality. In oneembodiment, the flow rate through the skimmer is at least 1 to 3 timesthe aquarium volume per hour.

The eductor of the present invention is contemplated for use in otherapplications besides a protein skimmer where up to three differentfluids are to be mixed. If more than one liquid or gas is to be mixedusing the eductor, multiple tubes can be positioned in the mixingchannel in a manner similar to tube 653 c, as shown generally in FIG. 20e.

In one embodiment, catholyte or anolyte is added to the protein skimmerthrough inlet 654. Preferably, the catholyte or anolyte is dripped intothe water as is flows through the inlet before it enters chamber 651. Inan alternative embodiment, the catholyte or anolyte is mixed with thewater through mixing eductor 653. In this embodiment, the catholyte oranolyte can be added through tubing 653 c. Alternatively, the catholyteor anolyte may be added to the water circulating through pipe 658, froman external source (not shown) and introduced through the mixing eductor653 a.

Referring back to FIG. 17 a, another alternative embodiment provides forflowing water from the anaerobic chambers to a conventional degassingtower 660 which puts oxygen into the water and raises the pH. In adegassing tower, water cascades down through plastic balls or over ascreen, breaking up the water and increasing the surface contact of thewater with air, thereby entraining air into the water. Such degassingtowers are well known in the art.

In yet another embodiment, water from the anaerobic chambers is suppliedto an oxytower 670 of the present invention, which is illustrated inFIGS. 18 a and 18 b. The oxytower removes nitrates, nitrites,phosphates, carbon dioxide and heavy metals from the water, as well asadds oxygen to the water. By oxygenating the water, the pH will remainmore stable than water that is oxygen deficient. Further, the oxytowerwill also help to cool the water by evaporation.

The oxytower of the present invention is in the shape of an invertedcone, having side walls 671 a that slope inward at an angle θ_(oxy) of,for example, 5 to 45 degrees, and more preferably 10 to 20 degrees, asshown in FIG. 18 a. A medium, such as a screen 672, is placed on theinner surface of the cone and serves as support for the growth of algaein the oxytower. A pipe 675 a or other means, such as a gutter, forchanneling water is located along the top inner circumference of theoxytower chamber. The pipe 675 a has a plurality of outlets 676, such asholes or jets, located along its outer circumference through which watermay be dripped or sprayed along the top surface of the screen. The pipe675 a is connected onto the wall of the oxytower by supports 675 b, asshown in FIG. 18 b. An artificial light 673 is applied to supportphotosynthesis by the algae growing on the screens. Alternatively, theoxytower may be placed so it is subjected to sunlight during the day.

During operation of the oxytower, water flows into pipe 675 a throughinlet 674, and is dripped or sprayed from outlets 676 onto the top ofthe screens 672. The water then drips down the screens by force ofgravity.

In one embodiment, shown in FIG. 18 c, the oxytower has two inlets 674,positioned at opposite ends of the chamber, which feed water into pipe675 a. The diameter of each outlet 676 varies, with smaller outletspositioned closer to the inlets, and larger outlets at positions furtheraway from the inlets along the circumference of the pipe. In thisfashion, the largest outlets are at the two positions along thecircumference of the pipe equidistant from the two inlets. Thisarrangement of outlets from smallest to largest allows water to bedistributed more evenly over the screens than if the outlets were thesame size. For example, this embodiment can distribute up to 300 gallonsor more of water per minute evenly over the screens.

As the water drips down the screen surface, the screen will break up thewater and cause an increase in surface area, which will allow for thewater to be effectively degassed. Additionally, algae growing on thescreens will remove unwanted contaminants in the water, such asphosphates, nitrates, nitrites and heavy metals, which the algae usesfor nutrients as it grows. The water then flows out of the tower throughoutlet 677. Water from the outlet may be passed through a strainer ormechanical filter 678 a for removing debris from the water. As shown inFIG. 18 a, a trap basket 678 b may be used for holding the removeddebris.

The flow of water through the tower may vary. For the oxytower to beeffective, it is preferable that the volume of water being treated passthrough the oxytower 2.5 times per day. It is more preferable that thevolume of water being treated pass through the oxytower once per hour.

While the walls of the oxytower are preferably inclined, as shown inFIG. 18 a, the walls, as well as the screens supported by the walls, maybe vertical, so that the oxytower has a cylindrical shape. The walls ofthe oxytower can be made of any neutral plastic (i.e., a plastic that isminimally reactive, or non-reactive, with the water being treated) thatis safe for aquatic life. Examples of suitable materials include PVC,polyethylene, polypropylene, methacrylic or acrylic plastic, fiber glassreinforced plastic (FRP), or stainless steel. The oxytower may have adiameter of up to 8 feet or more, and may have any practical height.

The screen 672 may be made from any material which is safe for aquaticlife and which is resilient and will not corrode in saltwater. Forexample, the screen may be made of soft nylon or fiberglass material.The screen may be one continuous piece, but is preferably in multiplepieces for easy cleaning. For example, the screen may have 4, 6, or 8sections. The screen may have various shapes, sizes and hatchingpatterns. In a preferred embodiment, the screen has a diamond shapecross hatching that is 3/16 inch to ¼ inch in length for each leg of thediamond. The screen, or screen sections are attached to a pre-formedplastic support. The plastic support is then attached to the inside ofthe tower. Alternatively, a medium other than screens may be used whichwill accomplish a similar function as the screens. For example, carpetmay be used in place of the screens.

During operation of the oxytower, the screens should periodically becleaned in order to promote the optimal growth of algae for removingcontaminants from the water. It is preferable that the entire surfacearea of the screen not be cleaned at one time. For example, in anembodiment where there are 4 sections of screen, it is preferable thatmore than 2 sections not be cleaned at one time. For best results, thescreens are cleaned periodically on a rotating bases, where one screenis cleaned, and then after the algae begins to grow on the cleanedscreen, another screen is then cleaned. The cleaning of the screensshould be done carefully so as not to remove the roots of the algae. Ifthe roots are removed, the algae will grow poorly and slowly.Preferably, the screens should not be bleached, pressure cleaned orcleaned with chemicals, so as not to harm the algae.

In one embodiment, catholyte is added to the oxytower. Preferably, thecatholyte is added to the water as it passes through inlet 674, beforeit flows into pipe 675 a. This way, the catholyte is mixed into thewater before it is flows out of outlets 676. The catholyte can be addedfrom an external source by any means known in the art, such as bydripping the catholyte into inlet 674.

The light source 673 may be any light source which will provide thenecessary light for photosynthesis and algae growth. The light sourcemay be natural or artificial light and may be provided either directlyor indirectly to the algae. In one embodiment, for example, where thesurface of the screen is 2 square inches per gallon of water to betreated, and the flow of water is 0 to 0.02 gal/min/square inch ofscreen surface, the light source preferably provides at least 0.75 wattsper 10 in² of screen surface, such as, for example 1 watt per 10 in² ofscreen surface. Examples of light sources include natural sunlight, apower compact tube, a high output (HO) or very high output (VHO)fluorescent bulb with a spectrum of 4000 K to 10,000 K. A metal halidebulb may also be used. In one embodiment, bulbs are mounted verticallyand continuously along the height of the oxytower. The light source 673should be placed a distance from the screens which will be effective forpromoting photosynthesis and growth of the algae. For example, where theabove HO or VHO fluorescent bulbs are used in the embodiment of FIG. 18a, the tower preferably has a maximum diameter of from 4 to 8 feet, inorder to optimize the distance from the screens to the light. For largerunits, metal halide bulbs may be used with or without reflectors. It ispreferable that the light remains on 24 hours per day for optimal algaegrowth.

The bulbs can be covered with a translucent acrylic or glass covering toprotect them from water. In larger units the protective covering 673 bwill preferably extend all the way through the unit and will haveopenings 673 c and 673 d to allow for improved ventilation, as shown inFIG. 19 a. The heat produced from the light will rise, which will causean elevated air current to suck in cool air from the bottom opening 673c of the protective covering 673 b and cool the light bulb 673 a. Anapparatus for moving air, such as a fan (not shown), can be added tofurther ventilate the light to make cooling more efficient.

In another embodiment, illustrated in FIG. 19 b, a stainless steel bar673 e is used to support multiple bulbs 673 a. In this embodiment, thenumber of lights is chosen to optimize the amount of light for improvedalgae growth and contaminant removal from the water.

In a preferred embodiment, shown generally in FIG. 19 c, the oxytowercontains a reflector 673 f in the shape of a cone. The reflector 673 fmay be positioned inside the oxytower by any means known in the art. Inone embodiment, the reflector 673 f is suspended from a support madefrom three members 673 g attached to the oxytower chamber at one end,and with the opposite end rising above the oxytower to intersect at apoint along the central axis of the tower, as illustrated more clearlyin FIG. 19 d, showing a top view of the oxytower. A 1000 watt light bulb673 a is placed in the space between the reflector, and the oxytowerchamber, and the reflector is preferably positioned such that all of thelight from the bulb is reflected on the screens containing the algaewithin the oxytower. The spectrum of light used should be as close tonatural sunlight as possible, ranging from 5000 K to 15,000 K,preferably 6000° K to 10,000° K. In one embodiment, where the diameterof the oxtower is 6 feet, 6 inches, and the walls of the oxytower have aslope of 50 degrees, the screens provide 42 square feet of surface areafor algae to grow. This embodiment allows for the 1000 watt bulb toprovide sufficient light to the entire screen surface area atapproximately 1.6 watts/square inch.

In another embodiment, the oxytower has a top cover 671 c, to preventunwanted debris from getting inside. The cover may be transparent toallow light, such as natural sunlight, into the chamber. The cover mayhave a chimney 671 d through which gas emissions from the oxytower maybe collected and/or vented. For example, the chimney may be filled withactivated carbon, which may be used to adsorb hydrogen sulfide gas.

The bottom of the chamber 671 b may be flat, or it may be conicallyshaped as shown in FIG. 18 a. The conical shaped bottom 671 b is betterfor collecting detritus.

An optional blower 679 may be used to blow air into the oxytower, whichwill increase evaporation in the tower and cool the water, as well ashelp to degas the water. If a blower is to be used to cool the water, itis preferable that the tower be insulated for improved coolingefficiency. Additionally, carbon dioxide may also be blown into theoxytower to raise oxygen levels in the water through increasedrespiration and production of oxygen by the algae.

The oxytower of the present invention is particularly suited for use incombination with at least aerobic and anaerobic chambers of the presentinvention, to treat and condition water in aquariums of 500 gallons ormore. However, the oxytower may be employed for smaller aquariums andmay be used in combination with any of the systems described herein. Inaddition, the oxytower of the present invention can be applied to otherapplications where water is to be treated, even in the absence of thedenitration methods and systems of the present invention. For example,the oxytower can be used in place of protein skimmers in standardcommercial applications.

Additionally, the oxytower is contemplated for use in a broad range ofother applications, such as for use in waste water treatment, drinkingwater purification, and other applications where it would be helpful toremove contaminants using algae.

A further process step, which may be added to any of the Nitrafixsystems described herein, can be used to reduce sulfate concentrations.As described above, the denitration process of the systems of thepresent invention results in increased levels of sulfates in the water.Additionally, there is the possibility that undesirable amounts ofhydrogen sulfide may also be produced at certain times, such as atstartup, after the denitration chamber has been shut down for a periodof time. Consequently, it may be desirable in some aquarium systems toreduce the level of sulfates and/or hydrogen sulfide.

Accordingly, a novel method and desulfator apparatus for reducingsulfate and hydrogen sulfide concentrations in aquarium water will nowbe described with reference to FIGS. 23 a to 23 c. The method andapparatus are not limited to use with the systems of the presentinvention, but could be used in any system where it is desirable toreduce sulfate concentrations.

The desulfator of the present invention utilizes anaerobicphotosynthetic bacteria to reduce sulfate levels in both fresh andsaltwater systems. Any type of anaerobic photosynthetic bacteria whichwill reduce sulfate levels may be used. Examples of such bacteria mayinclude, purple bacteria, purple nonsulfur bacteria, and/or green sulfurbacteria, such as Chromatium vinossum, Thiospirillum jenense,Rhodospirillum rubrum, Rhodobacter sphaeroides, Chlorobium limicola,Prosthecochloris aestuarii. In the presence of light, these bacteriawill use photosynthesis to break down sulfates and/or other sulfurcompounds in the water.

One preferred embodiment of a desulfator apparatus 680 is illustrated inFIG. 23 a. The desulfator apparatus of this embodiment preferablycomprises a chamber 700, which contains media 703 for supporting thesulfur bacteria, a light source 702, as well as inlet 701 and outlet704, for allowing water to flow in and out of the chamber.

The chamber 700 can be any shape, but is preferably a cylindrical shapedchamber having an outer cylinder 705 and an inner cylinder 706concentrically arranged inside the outer cylinder. The walls of thechamber are preferably transparent to light, and may be made of, forexample, a clear acrylic plastic. The media 703 for supporting thebacteria is contained between walls 705 and 706, as illustrated in FIG.23 b. The portion of the chamber containing the media should be airtight, so as to not allow the introduction of oxygen into the chamber. Avent 710 having a valve 711 may be used to allow exhaust gasses producedwithin the chamber to escape. Valve 711 is a one way flow valve,allowing the flow of gases out of, but not into, the chamber.

In one embodiment, catholyte is added to the desulfator apparatus tohelp grow bacteria. The catholyte is added to the apparatus from anexternal source, and can be added by any means known in the art.Preferably, the catholyte is added by dripping the catholyte into thewater as it flows through inlet 701, before it enters chamber 700. Thecatholyte is added in an amount that ranges from about 1 to about 20percent of the volume of the water flowing through the system.

The support media 703 is preferably transparent to light. For example,the media may be a clear biofilm, such as, Kaldnes, which is made byWMT. Other media like Bio-Chem stars from RENA may also be used. Thesurface area provide by the media is preferably relatively large. Forexample, the media may have an average surface area of 500 square metersper cubic meter or greater, and more preferably an average surface areaof 850 square meters per cubic meter or greater.

The ratio of the height of the chamber to the diameter of the chamber ispreferably from 3 to 5, in order to allow for sufficient contact timebetween the water and the bacteria supporting media.

The light used in the chamber can be either natural sunlight orartificial light, or both. For example, a light source 702 a may extenddown through the inside of cylinder 706, as shown in FIGS. 23 d, 23 eand 23 f, in order to provide light throughout the chamber. FIG. 23 dillustrates the use of an HO or VHO tube, which must be connected to apower source at both ends 702 b and 702 c. FIG. 23 e illustrates the useof metal halide or incandescence bulbs 702 b, which may be arrangedvertically down the center of the chamber as shown, in order to providethe desired amount of light to the bacteria. FIG. 23 f illustrates thisuse of a power compact tube 702 b, which has the advantage of beingconnected to the power source at only one end. The cylinder 706 may beopen at its ends in order to allow for ventilation to the light source,as shown for example in FIG. 23 d. An apparatus for moving air, such asa fan 713, as illustrated in FIG. 23 e, may be used with any of thedisclosed light sources to increase the amount of ventilation throughthe cylinder 706.

Because the walls 705 and 706 and the media 703 are transparent to thelight from the light source, a maximum amount of the volume of thechamber housing the bacteria is exposed to the light, thus increasingthe efficiency of the chamber. The spectrum of light used is preferablya day spectrum light from 4000 K to 25,000 K. The light may be left oncontinually for increased efficiency.

The flow of water through chamber 700 is preferably from bottom to top,in order to avoid clogging. Additionally, as shown in FIG. 23 c, screens712 may be placed in front of the inlet 701 and outlet 704 to preventclogging and to contain the media in the chamber. The flow rate of waterthrough the chamber may be adjusted to allow for the desired amount ofsulfate reduction. Because the bacteria used in the desulfator apparatusare anoxygenic, it is preferable that the water entering the chamberhave a low oxygen content. If necessary, a system for reducing oxygencontent of the water may be utilized to reduce the oxygen concentrationbefore the water enters the chamber.

Yet another preferred embodiment of a system for filtering andconditioning water will now be described with reference to FIG. 26 a.While the system is designed for use with larger aquariums, it may beused for any size aquarium. The system may also be used for maintainingthe water of aqua tanks, where fish are raised in aqua cultureapplications.

Water flows from aquarium or aqua tank 116 to a filter 101. This filteris preferably a mechanical filtration device which allows the water topass through the filter without pressurization from a filter pump, thussaving power. However, any filter known in the art may be used,including filters requiring a filter pump. The filter removesparticulates from about 30 microns to about 200 microns from the water.Examples of filters which are known in the art include a drum filter, adisk filter, and a sock filter.

Water next flows from filter 101 to a sump 102. Sump 102 preferably hasa volume which is large enough to prevent overflow of water from thesystem when the system is stopped. Both mechanical filter 101 and sump102 may be placed at elevations which are lower than aquarium or aquatank 116 in order to allow water to run from the aquarium or aqua tank116 to the mechanical filtration device and sump by force of gravity,which will save energy and lower the cost of operation. If filter 101and sump 102 are not placed at elevations lower than aquarium 100, thena pump may be used to pump water from aquarium 100 to filter 101 andsump 102.

From sump 102, water flows to a number of other processing apparatuswhich further purify and condition the water. These apparatus include abio-filter 107; a protein skimmer 109; an oxytower 110; a denitrationsystem 112, a desulfator 111; an optional heater or chiller 114 foradjusting the temperature of the water; and a UV sterilizer 113, forsterilizing the water before it returns to aquarium or aqua tank 116.

As shown in FIG. 26 a, a portion of the water flows from the sump tobio-filter 107, then to protein skimmer 109, and then to oxytower 110.The remaining water flowing from the sump flows to denitration system112 and desulfator 111, and then to oxytower 110. The percentages ofwater flowing from the sump to bio-filter 107 and from the sump todenitration system 112 may be adjusted to achieve the desired waterconditions. In one embodiment, for example, about 90% to about 99% ofthe water flows from the sump to bio-filter 107, while about 1% to 10%flows from the sump to denitration system 112. More preferably about 97%to about 99% of the water flows from the sump to bio-filter 107, whileabout 1% to about 3% flows from the sump to denitration system 112.

From oxytower 110, the water may flow through an optional heater orchiller, in order to maintain the water in aquarium or aqua tank 116 atan acceptable temperature for the fish. Heaters and chillers are wellknown in the aqua culture art. The water then flows through UVsterilizer 113, which kills any microorganisms in the water, such asbacteria, which may be harmful to the fish, before flowing back to theaquarium. Such UV sterilizers are also well known in the art.

As shown generally in FIG. 26 b, catholyte can be added to the systemfrom source 160 in a number of places. In one embodiment, as shown inFIG. 31 a, catholyte is added directly to a tank 116 for holding aquaticlife. Pump 116 a removes water from the tank, and circulates it backinto the tank through mixing eductor 116 b. Catholyte is provided froman external source 160, and is added through an inlet tube leading intothe mixing eductor. This embodiment not only mixes the catholyte withwater from the tank, but it also promotes the thorough mixing of thewater/catholyte mixture throughout the entire tank.

In another embodiment, depicted in FIG. 31 b, a mixing eductor 116 b ispositioned to accept a flow of water from the outlet of the filtrationsystem 116 c, and to create a flow of water into tank 116. Catholyte isadded through an inlet tube of the mixing eductor.

Alternatively, catholyte can be added directly from external source 160into tank 116, preferably by dripping the solution into the tank.

Bio-filter 107 uses aerobic bacteria processing to treat the water toreduce ammonia to nitrite and nitrite to nitrate. The water to betreated is flowed through a chamber which contains a support media onwhich the aerobic bacteria may colonize. An oxygen-containing gas isintroduced into the chamber to improve the efficiency of the aerobicbacteria process.

One embodiment of a bio-filter is illustrated in FIG. 27. In thisembodiment, bio-filter 107 comprises a tank 108. Preferably the lowerportion of which has a tapered shape to collect sediment which settlesto the bottom, although it may have a flat bottom. For example, tank 108may be in the shape of cylinder with a cone shaped bottom. A drain 326 aand valve 326 b can be included in the bottom of tank 108, to allowsediment to be periodically removed. If desired, a clear section of pipe326 c may be employed to allow visual inspection of the drain so thatsediment buildup may be monitored. A lid 106 may be used to cover thetank 108.

In another embodiment, illustrated in FIG. 28, a two valve drain systemmay be used to collect solid matter settling to the bottom of the tankin a way that minimizes water loss from the tank. An upper valve 206 apositioned in the drain pipe remains open during normal functioning ofthe tank, while a lower valve 206 b, remains closed. This allows thewaste settling to the bottom of the tank to move through the drain pipeand collect in sediment collector 205 a. Collector 205 a preferably isin the shape of a diamond.

Water from the tank will flow through upper valve 206 a and into watertube 205 b, which provides fluid connection between the collector 205 alocated between valves 206 a and 206 b and the open air. After solidsbuild up in the collector 205 a, they are removed by closing valve 206 aand opening valve 206 b. The solids will drain through valve 206 b, andthe water from water tube 205 b will flush any remaining solids from thewalls of collector 205 a. This allows the solid matter to drain withoutremoving excess water from tank 101, instead using only the water inwater tube 205 b. Water tube 205 b extends to at least the height of thetank itself, and therefore water will fill the water tube until itreaches a level that is in equilibrium with the level of water in thetank. In an alternative embodiment, water tube 205 b contains a tank 205c to provide a larger volume of flushing water than the volume of thetube alone.

All or a portion of collector 205 a may be clear so that the level ofsolids collected in the pipe section may be visually monitored, andvalves 206 a and 206 b may be opened and closed manually. Alternatively,valves 206 a and 206 b can be controlled electronically, so that theyopen and close automatically. In this embodiment, a sensor could be usedto determine the level of solid in the collector, and send a signal tothe drains to open and close as necessary to drain the pipe section. Anysensors and automatic valves known in the art can be used with thisembodiment of the present invention.

This embodiment is not limited to use with the bio-filter discussedabove. Indeed it is compatible with most of the tanks discussedaccording to the present invention.

Referring again to FIG. 27, the bio-filter chamber has an inlet 111 andan outlet 121 through which water can enter and exit the chamber. Ascreen 101 is preferably placed over the outlet and inlet to avoidclogging and contain the media within the chamber. The height H1 of theoutlet pipe 121 a will control the level of water in the bio-filter 107.In one embodiment, catholyte is added to the bio-filter such thatcatholyte is dripped directly into tank 108. In another embodiment,catholyte is added to the water upstream of tank 108 and then flows intobio-filter 160 through inlet 111. The addition of catholyte in thebio-filter will improve the health of the bacteria and will help thebacteria grow. The improved health of the bacteria will in turn improvethe water quality and allow for more efficient filtration. Bio-filter107 may be partially or completely filled with support media 112, whichacts as a substrate for the aerobic bacteria. The aerobic bacteriaalready exist in the water of the aquarium and will readily colonize onthe media. The media 112 may be any type of media that can supportcolonization of aerobic bacteria. While a media having any practicalsize and shape may be used, media having a high surface area ispreferred. For example, sand, crushed coral and other media havingrelatively high surface areas may be used. One preferred form of supportmedia is plastic, preferably in the form of small spheres or tubes,although any shape known in the art may be used. The plastic media islightweight and may float in the aquarium water. It does not clogeasily, and provides a large surface area for bacterial colonization.One example of such a plastic media is known as biofilm. Examples ofbiofilm which may be used include Kaldnes and Bee-Cell, which aremanufactured by Water Management Technologies, Inc. Other media likeBio-Chem stars from RENA may also be used.

A mixing eductor 653, is used to eject an oxygen-containing gas or aliquid into the tank. The bubbles are well mixed with the water in thetank by mixing eductor 653, which comprises an inlet channel 653 a, amixing chamber 653 b, and a tubing 653 c. A pump 656 circulates waterfrom bio-filter 107 through pipe 658 to the inlet channel 653 a, wherethe water is forced through the mixing chamber 653 b and mixed with thegas or liquid from tubing 653 c and additional water entrained by themixing eductor from the bio-filter. In an alternative embodiment, thewater going to eductor inlet channel 653 a is supplied from a sourceoutside the bio-filter chamber, such as from the sump or the aquariumitself. Mixing eductor 653 and its operation are described above in moredetail with reference to FIGS. 21 a to 22 b.

In one embodiment, catholyte is added to the bio-filter 107 through asecond tube which is positioned in the mixing channel in a mannersimilar to tube 653 c used to add the oxygen to the eductor, such thatit is forced through the mixing chamber of the eductor, and mixed withthe water in the chamber. In another embodiment, mixing eductor 653 issupported inside bio-filter 107 by a support 657, in the mannerillustrated in FIGS. 30 a and 30 b. As shown in FIG. 30 b, the mixingchamber 653 b is supported by a plate 657 c, so that the inlet cone ofthe mixing eductor is contained inside a small chamber composed ofperforated plates, or screens, 657 a, the top plate 657 c and a bottomplate 657 b. Water flowing through the perforated plates or screens 657a is entrained into the inlet cone of mixing chamber 653 c.

In a preferred embodiment, as shown in FIG. 29, both the inlet 111 andoutlet 121 are located towards the top of the tank. The inlet is fittedwith a check valve and the outlet is fitted with a screen to prevent anymedia from escaping. The lower portion of the tank has a cone-shapedbottom, with walls that slope downward, preferably at an angle of 5degrees from horizontal. The mixing eductor 653 is positioned along theinner surface of the tank to force the water to flow around the insideof the tank in a circular direction. Additionaly, a strainer 157 isplaced around the eductor to prevent it from becoming clogged. In thisembodiment, the circular flow of water through the media provides forlonger contact time, and thus better filtration.

The aerobic bacteria exist and thrive in the water and will colonize onthe media within the bio-filter chamber as the system is operated. Thetype of aerobic bacteria utilized in bio-filter 107 may include, forexample, nitrosomonas and nitrobacter bacteria. These naturallyoccurring bacteria break down ammonia and nitrites in the water and formnitrates.

The flow rate through the bio-filter may be optimized to achieve thedesired water quality. For example, the flow rate through the bio-filtermay range from 1 to 30 times the volume of the aquarium per hour, andmore preferably from 3 to 10 times per hour.

The water from bio-filter 107 flows to protein skimmer 109. The purposeof the protein skimmer is to remove contaminants, such as undesirableorganic matter, otherwise known as dissolved organic compounds (DOC),from the water, as well as to increase the oxygen level of the water.Any protein skimmer known in the art may be used for this application.

One preferred embodiment employs a novel protein skimmer which utilizesa mixing eductor to introduce bubbles into the water. This novel proteinskimmer is described above in connection with FIGS. 20 a to 20 c.

The flow rate through the protein skimmer may be optimized to achievethe desired water quality. For example, the flow rate through theprotein skimmer may range from 1 to 30 times the volume of the aquariumper hour, and more preferably from 3 to 10 times per hour.

Water from protein skimmer 109 flows to oxytower 110, which utilizesalgae to remove phosphates, sulfates and nitrates from the water. Theoxytower may also add oxygen to the water. By oxygenating the water, thepH will remain more stable than water that is oxygen deficient. Further,the oxytower will also help to cool the water by evaporation. A detaileddiscussion of the oxytower is provided above in connection with FIGS. 18a to 19 b. In an alternative embodiment, a supply of catholyte is addedto the water as it flows to the oxytower.

As discussed above, a portion of the water flowing from the sump isflowed to a denitration system 112, which is used to reduce nitrateconcentrations in the water. In order to manage nitrate levels in thewater, any denitration system known in the art may be employed. In oneembodiment, a supply of catholyte is added to the water as it flows tothe denitration system.

In a preferred embodiment, the denitration system 112 is a Nitrafixsystem, as described herein above. Any of the Nitrafix systems describedabove could potentially be used. Preferably, the Nitrafix system usedwould comprise an optional filtration step 1, in which the water to betreated passes through a filter (not shown); an optional aerobicbacteria processing step 2; an anaerobic bacteria processing step 3; andan optional step 4, wherein one or more calcium reactors are employedfor maintaining pH and adding calcium.

For large commercial applications, the denitration system 112 preferablyemploys the systems described in connection with FIG. 17 a above. Forexample, an aerobic chamber 610, one or more denitration chambers 620and optionally one or more calcium chambers 630, could be used. Forexample, in one preferred embodiment, the aerobic chamber is the chamberdescribed in connection with FIG. 24; the denitration chamber is chosenfrom one of the chambers described in connection with FIGS. 9 and 11;and either no calcium chamber, or one or more calcium chambers, asdescribed in connection with FIG. 25 are employed. In yet anotherembodiment, only one or more denitration chambers 620 are employed, withno aerobic chamber, and with either no calcium chamber, or one or morecalcium chambers.

Alternatively, the denitration system 112 preferably employs theNitrafix system described in connection with FIGS. 2 a to 6 above. Forexample, an aerobic chamber 110 is employed, either with no calciumchamber or with one or more calcium chambers. In yet another embodiment,a denitration chamber 120 is employed, either with no calcium chamber orwith one or more calcium chambers. If calcium is used, a single sourceor multiple sources of calcium may be employed.

In an alternative embodiment, the chambers of the Nitrafix system arearranged in a single container, as described in FIGS. 8 a to 8 c or FIG.15.

In yet another embodiment, a further process step is added after thedenitration system 112 described herein to reduce sulfateconcentrations. As described above, the denitration process of thesystems of the present invention results in increased levels of sulfatesin the water. Additionally, there is the possibility that undesirableamounts of hydrogen sulfide may also be produced at certain times, suchas at startup, after the denitration chamber has been shut down for aperiod of time. Consequently, it may be desirable in some aqua culturesystems to reduce the level of sulfates and/or hydrogen sulfide.Accordingly, the novel method and desulfator apparatus, described abovewith reference to FIGS. 23 a to 23 f, may be employed for reducingsulfate and hydrogen sulfide concentrations in the water. Alternatively,any system known in the art for reducing sulfate in the water may beemployed.

Referring back to FIG. 26 a, a monitoring system 115 may be used tomonitor the properties of the aqua tank water, such as temperature, pH,salinity, dissolved oxygen, ORP (water conductivity), flow, pressure,levels, and power failure. The parameters of the water treating systemof FIG. 26 a may then be controlled based on the feed back frommonitoring system 115. For example, the ORP, which is a measure of waterconductivity, may be used to control ozone levels in the proteinskimmer, since ozone cleans the water and thus affects the waterconductivity.

In some instances, it may be necessary to clean the aquarium oraquaculture tank for holding or growing fish. For example, in fishfarms, when a crop of fish is removed from a tank to be harvested, thefarmers clean the tank before beginning to harvest the next crop.Similarly, when fish become sick, they need to be treated and the tankalso needs to be sterilized to remove any contaminants, such as harmfulbacteria. In these situations, anolyte can be used in conjunction withthe systems of the present invention to sterilize the water and theequipment it comes into contact with. Since the anolyte couldpotentially kill the bacteria necessary for the bio-filter, denitrator,and other bacteria containing filters to operate, the anolyte will notbe added into these filters. For example, in one embodiment, the flow ofwater from the tank can be cut off from most of the filtration systemsuch that the flow of water is directed only to a protein skimmer andreturned back into the tank. Animals, if any can remain in the tankduring the treatment with anolyte. The anolyte can be added from anexternal source in a number of different ways, including by directlyadding the anolyte to the aquaculture tank, such as by dripping.Additionally, the tank can be equipped with a mixing eductor and pump,such as the one used to add catholyte in FIG. 31 a. During the time inwhich the filtration system is cut off from the tank, the bacteria inthe filtration system that live off of contaminants and bi-productsreleased by the aquatic life in the tanks can be kept alive, forexample, by adding ammonium salt to the chambers containing thebacteria.

In one embodiment, the amount of anolyte added can be monitored by asensor such as monitoring system 115 in FIG. 26 a. One such sensor knownin the art is the ORP system. As the quality of the water improves, theORP can be used to automatically stop the addition of anolyte when theconductivity in the water reaches a certain point.

After the water is cleaned and the fish are healthy, substantially allof the anolyte must be removed from the water, or rendered inactive,before it is circulated through the filtration system. In oneembodiment, catholyte is added to the water to neutralize the anolyte.

Additional water may occasionally need to be added to the system ofFIGS. 26 a and 26 b. If so, the water may be supplied, for example, by areverse osmosis unit 103, which may be used to filter city water andmake it safe for the fish.

In one embodiment, water is pumped to bio-filter 107 and the denitrationchamber 112 using a pump 104, as shown in FIG. 27. Alternatively, thebio-filter 107 and denitration chamber 112 are placed at higherelevations than the other chambers in the system, including the proteinskimmer, the oxytower and the desulfator, so that the water will run byforce of gravity through these chambers and back to aquarium 100, thussaving power. In another embodiment, a separate pump is used to pumpwater to the other chambers, such as the protein skimmer, the oxytowerand the desulfater. Pump 104 is preferably a type of pump which consumesrelatively low energy, such as a flow pump. Pumps 106 and 108, as shownin FIG. 26 a, may be, for example, pressure pumps. Other types of pumpsknown in the art may also be used for pumps 104, 106 and 108.

The system of FIGS. 26 a and 26 b may be modified according to thedesired water quality to be obtained and the cost of the system. Forexample, in one embodiment, desulfator 111 is not employed in the systemof FIG. 26, so that the water flows directly from denitration chamber112 to oxytower 110. In yet another embodiment, protein skimmer 109 isnot employed, so that the water from bio-filter 107 flows directly tooxytower 110. In yet another embodiment, oxytower 110 is omitted, sothat water flows from bio-filter 107 and either the desulfator 111, orthe denitration chamber 112 (if the desulfator is not employed), to theprotein skimmer 109, and then from the protein skimmer 109 to aquariumor aqua tank 116, via the optional chiller/heater and UV sterilizer. Instill another embodiment, the order of the protein skimmer and oxytowerare reversed, so that water flows from the bio-filter 107 to theoxytower 110 and then to the protein skimmer 109, and then down to theaquarium via the optional chiller/heater and UV sterilizer. In this lastembodiment, water may flow from either the desulfator 111, or thedenitration chamber 112 (if the desulfator is not used) to either theprotein skimmer 109 or the oxytower 110. In yet another embodiment, theprotein skimmer, oxytower and desulfator are all omitted, so that waterflows from the denitration chamber 112 to the bio-filter 107, and fromthe bio-filter 107 to the aquarium, via the optional chiller/heater andUV sterilizer. In yet another embodiment, the flow through the oxytowerand skimmer may be in parallel so that water flows from the bio-filter107 to the skimmer and the oxytower at the same time and then down tothe aquarium via the optional chiller/heater and UV sterilizer.

In yet another embodiment, the flow of water from the bio-filter outletmay be split, so that only a portion of the water from the outlet ofbio-filter 107 flows to the skimmer 109, while the remaining portionflows to either the chiller/heater and UV sterilizer or directly to theaquarium. For example, ⅓ of the water from the bio-filter may flow tothe protein skimmer, while ⅔ of the flow goes to the aquarium via theoptional chiller/heater and UV sterilizer.

In all the embodiments listed herein, both the UV sterilizer 113 and thechiller or heater 114 may be omitted. Additionally, a sump need not beemployed, but instead the water may be pumped and returned directly tothe aquarium tank.

Other flow arrangements are also contemplated. For example, each of thechambers, including denitration chamber 112, desulfator 111, oxytower110, protein skimmer 109 and bio-filter 107, may be used separately, sothat the water from either the sump or the aquarium may be floweddirectly to each chamber, and then returned directly back to either thesump or the aquarium. Still other flow arrangements and configurationsare possible, as may be appreciated by one of ordinary skill in the art.

The systems of FIGS. 26 a and 26 b may be assembled in a compact manneron a single support, known as a “skid.” This would allow the system tobe manufactured and assembled off-site and then shipped to the aqua tanklocation ready to be used. Such an integrated system would also likelycost less than a system built on site.

EXAMPLE

With respect to the flow rate of water through the system of the presentinvention, flow rates within the range of 5 to 7 gph were found to beworkable for a denitration chamber made according to the embodimentshown in FIG. 14, for aquariums ranging in size from 250 to 500. Flowrates in the range of 3 to 5 gph were found to be acceptable fordenitration chambers of that type where the aquariums being serviced arewithin the range of 50 to 500 gallons. When the system is originallyplaced on-line, a flow can be adjusted through the valve system. One wayof adjusting the flow is to place a glass of a given volume at theoutlet so that the flow can be measured and adjusted, until the desiredflow rate is achieved. In addition, if the nitrate level is greater thandesired, such as 5 ppm after the system has operated for 30-90 days, theflow rate can be adjusted at a higher level, to achieve the desirednitrate level.

The biological systems disclosed in this application can be used forboth salt and fresh water aquariums, as well as brackish wateraquariums. The systems may be used for both cold water and heatedaquariums. Heating the aquarium water to a temperature range whichallows the bacteria to be efficient before it enters the biologicalsystems of the present invention may provide improved results. Forexample, if Thiobacillus denitrificans are employed, the water in thechamber should preferably have a temperature ranging from 25 to 30degrees Celsius.

While the methods, devices, and systems of the present invention havebeen disclosed for use in treating water for aquariums, all or aspectsof the disclosed inventions can also be used in other applications wherewater must be treated. For example, the denitration methods and systemscan be used, along with other apparati and methods, in fish farms, hogfarms, and other applications where high levels of nitrates are producedand need to be removed and/or treated.

While certain materials may have been disclosed for construction of thevarious chambers, piping and other parts of the systems disclosedherein, it will readily be recognized that other materials known in theart may also be used.

While the invention has been disclosed herein in connection with certainembodiments and detailed descriptions, it will be clear to one skilledin the art that modifications or variations of such details can be madewithout deviating from the general concept of the invention. Thus theinvention is to be limited by the claims, and not by the embodiments anddetailed description provided above.

A biological system according to the present invention which was similarto the embodiment illustrated in FIG. 8 was used to filter a 500 gallonaquarium containing relatively large numbers of fish. The tank initiallyhad a nitrate concentration of approximately 50 ppm. After three weeksof conditioning the water with the above mentioned biological system,the nitrate content of the aquarium was reduced to a safe level, under 5ppm NO₃ ⁻, and was maintained at about that level for several months.

1. A process for conditioning water in a contained environment foraquatic life, the process comprising the step of: adding a sufficientamount of catholyte to the water to promote the health of the aquaticlife wherein the total amount of catholyte in the water ranges fromabout 1 to about 20 percent of the total volume of the water in thecontained environment.
 2. The process of claim 1 wherein the totalamount of catholyte in the water ranges from about 5 to about 20 percentof the total volume of the water in the contained environment.
 3. Theprocess of claim 1 further comprising the steps of flowing an amount ofwater from the contained environment to a first apparatus for treatingthe water.
 4. The process of claim 3 wherein catholyte is added to thewater as it flows into the first apparatus.
 5. The process of claim 3wherein the first apparatus performs the process of substantiallyreducing the oxygen concentration of the water in the flow.
 6. Theprocess of claim 5 further comprising the step of flowing the water fromthe first apparatus to a second apparatus containing anaerobic bacteriafor substantially reducing the level of nitrates in the water.
 7. Theprocess of claim 6 wherein the catholyte is added to the water before itflows into the first apparatus.
 8. The process of claim 7 furthercomprising the step of adding catholyte to the water after it flows outof the first apparatus and before it flows into the second apparatus. 9.The process of claim 6 wherein the catholyte is added to the water as itflows from the first apparatus to the second apparatus.
 10. The processof claim 6 wherein the first apparatus comprises a first chambercontaining a first media supporting sufficient aerobic bacteria tosubstantially reduce the oxygen content in the water as the water flowsthrough the first chamber.
 11. The process of claim 10 wherein the firstchamber reduces the oxygen content of the water to a level of less than2 ppm.
 12. The process of claim 10, wherein the second apparatuscomprises a second chamber containing a media of sulfur which supportssufficient anaerobic bacteria to substantially reduce the nitratecontent in the water, as the water flows through the second chamber. 13.The process of claim 12 wherein the second chamber reduces the nitratecontent of the water to a level ranging from 0 to 20 ppm.
 14. Theprocess of claim 12 further comprising the additional step of addingcalcium to the water by flowing the water having reduced levels ofnitrates to a third apparatus containing one or more sources of calciumbefore the water flows to the contained environment.
 15. The process ofclaim 14 further comprising the additional step of adding catholyte tothe water as it flows from the second apparatus to the third apparatus.16. The process of claim 14 further comprising the step of degassing theflow of water before the water flows back to the contained environment.17. The process of claim 14 wherein the water flowing as it leaves thethird apparatus has a pH within the range of from about 6 to about 8.18. The process of claim 12 wherein the anaerobic bacteria compriseThiobacilus denitrificans bacteria.
 19. The process of claim 18 wherethe aerobic bacteria comprise at least one bacteria chosen fromnitrosomonas and nitrobacter bacteria.
 20. The process of claim 12wherein the anaerobic bacteria comprise at least one bacteria chosenfrom Thiobacilus denitrificans, Thiobacillus versutus, Thiobacillusthyasiris, Thiosphaera pantotropha, Paracoccus denitrificans, andThiomicrospira denitrificans.
 21. The process of claim 12 wherein thestructure of the second chamber is opaque and designed to minimize theapplication of any light to the anaerobic bacteria in the secondchamber.
 22. The process of claim 12 further comprising the step ofadding oxygen to the water after the water flows from the second chamberand before the water flows back to the contained environment.
 23. Theprocess of claim 12 further comprising the additional step of flowingthe water from the second chamber to a protein skimmer before the waterflows to the contained environment.
 24. The process of claim 23 furthercomprising the additional step of adding catholyte to the water afterthe water leaves the second chamber and before it flows into the proteinskimmer.
 25. The process of claim 23 wherein the protein skimmer bothraises the pH and adds oxygen to the water.
 26. The process of claim 23wherein the protein skimmer mixes an oxygen-containing gas with water inthe protein skimmer using a mixing eductor.
 27. The process of claim 12further comprising the additional step of flowing the water havingreduced levels of nitrates to an oxytower before the water is returnedto the environment for holding aquatic life, wherein the oxytowerincludes an enclosure for accepting a flow of water, the enclosurehaving side walls that slope inward at an angle θ_(oxy) from vertical; amedium is placed on the inner surface of the sidewalls and serves assupport for the growth of algae in the oxytower, and the water flowsdown the side walls while contacting the algae in a manner which allowsthe algae to effectively remove contaminants from the water and raisethe pH of the water.
 28. The process of claim 27 further comprising theadditional step of adding catholyte to the water after before in flowsinto the oxytower.
 29. The process of claim 12 further comprising thestep of reducing the sulfate concentrations in the water after it leavesthe second chamber and before the water flows back to the containedenvironment.
 30. The process of claim 29 wherein the step of reducingthe sulfate concentrations is achieved by introducing the water to adesulfator, wherein the desulfator includes an enclosure for accepting aflow of water, wherein the enclosure contains a media on which anaerobicphotosynthetic bacteria are supported, and the water flows through theenclosure while contacting the media in a manner which effectivelyreduces sulfate levels.
 31. The process of claim 30 further comprisingthe additional step of adding catholyte to the water as it flows intothe desulfator.
 32. The process of claim 30, wherein the anaerobicphotosynthetic bacteria comprise at least one bacteria chosen fromChromatium vinossum, Thiospirillum jenense, Rhodospirillum rubrum,Rhodobacter sphaeroides, Chlorobium limicola, and Prosthecochlorisaestuarii.
 33. The process of claim 1 wherein the catholyte isperiodically added to the water.
 34. The process of claim 1 wherein thecatholyte is added continuously to the water over a prolonged period oftime.
 35. The process of claim 1 wherein the catholyte is added to thewater by use of a mixing eductor.
 36. A process for conditioning waterin a contained environment for aquatic life, the process comprising thesteps of: removing a portion of the water from the contained environmentand placing the removed water in a separate environment, to therebypreserve the beneficial bacteria in the removed water; adding asufficient amount of anolyte to the water in the contained environmentto substantially eliminate harmful bacteria in the water, to therebypromote the health of the aquatic life; and adding the removed waterback to the controlled environment, after anolyte decomposes to aninactive state.